Docente
UFU
Roberto H. Miwa
Publicações
2026
Conceição, Victor M. S.; Pacine, Dominike; Morbec, Juliana M.; Miwa, Roberto H.
Self-assembly and Electronic Properties of Graphyne and Graphdiyne Molecular Wires on Metallic Surfaces Miscellaneous
2026.
@misc{daconceição2026selfassemblyelectronicpropertiesgraphyne,
title = {Self-assembly and Electronic Properties of Graphyne and Graphdiyne Molecular Wires on Metallic Surfaces},
author = {Victor M. S. Conceição and Dominike Pacine and Juliana M. Morbec and Roberto H. Miwa},
url = {https://arxiv.org/abs/2608.24925},
year = {2026},
date = {2026-08-18},
urldate = {2026-01-01},
abstract = {Molecular self-assembly on solid surfaces has been the subject of extensive research, motivated by both fundamental and technological interests. On the fundamental side, these studies seek to elucidate the mechanisms governing molecular self-assembly and the resulting surface structures. From an applied perspective, they provide a route toward controlling surface reactions and engineering molecular electronic devices. Here, based on first-principles density functional theory calculations, we present a comprehensive study of self-assembled molecular wires (MWs), composed of graphyne (GY(1D)) and graphdiyne (GYD(1D))-like structures, adsorbed on Au(111), Ag(111), and Al(111) surfaces. Our total-energy calculations reveal that non-aligned MW arrays are energetically preferred on all three metal substrates. The GY(1D) and GYD(1D) molecular wires interact with the metal surfaces through van der Waals (vdW) forces, while their molecular orbitals do not contribute to the formation of metallic interface states. Simulated X-ray photoelectron spectroscopy (XPS) spectra reveal that the C 1s spectral features of the molecular wires are largely preserved upon adsorption, while the absolute binding energies undergo a substantial downshift that is nearly independent of the metal substrate, indicating that metallic screening effects dominate the adsorption-induced core-level shifts. Electronic band-structure calculations further show that the semiconducting character of the molecular wires is retained, resulting in vdW metal-semiconductor heterostructures in which the semiconducting component consists of one-dimensional semiconducting channels. These findings demonstrate that self-assembled graphyne- and graphdiyne-based molecular wires on metal surfaces provide a promising platform for the realization of low-dimensional molecular electronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
Molecular self-assembly on solid surfaces has been the subject of extensive research, motivated by both fundamental and technological interests. On the fundamental side, these studies seek to elucidate the mechanisms governing molecular self-assembly and the resulting surface structures. From an applied perspective, they provide a route toward controlling surface reactions and engineering molecular electronic devices. Here, based on first-principles density functional theory calculations, we present a comprehensive study of self-assembled molecular wires (MWs), composed of graphyne (GY(1D)) and graphdiyne (GYD(1D))-like structures, adsorbed on Au(111), Ag(111), and Al(111) surfaces. Our total-energy calculations reveal that non-aligned MW arrays are energetically preferred on all three metal substrates. The GY(1D) and GYD(1D) molecular wires interact with the metal surfaces through van der Waals (vdW) forces, while their molecular orbitals do not contribute to the formation of metallic interface states. Simulated X-ray photoelectron spectroscopy (XPS) spectra reveal that the C 1s spectral features of the molecular wires are largely preserved upon adsorption, while the absolute binding energies undergo a substantial downshift that is nearly independent of the metal substrate, indicating that metallic screening effects dominate the adsorption-induced core-level shifts. Electronic band-structure calculations further show that the semiconducting character of the molecular wires is retained, resulting in vdW metal-semiconductor heterostructures in which the semiconducting component consists of one-dimensional semiconducting channels. These findings demonstrate that self-assembled graphyne- and graphdiyne-based molecular wires on metal surfaces provide a promising platform for the realization of low-dimensional molecular electronic devices.
Mendonça, Henri G.; Souza, Pedro H.; Orellana, Walter; Miwa, Roberto H.
Understanding the Oxygen Reduction Reaction and Oxygen Evolution Reaction in Metal Intercalated Biphenylene Bilayers Miscellaneous
2026.
@misc{mendonça2026understandingoxygenreductionreaction,
title = {Understanding the Oxygen Reduction Reaction and Oxygen Evolution Reaction in Metal Intercalated Biphenylene Bilayers},
author = {Henri G. Mendonça and Pedro H. Souza and Walter Orellana and Roberto H. Miwa},
url = {https://arxiv.org/abs/2608.07782},
year = {2026},
date = {2026-08-07},
urldate = {2026-01-01},
abstract = {We conducted an {it ab initio} study of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in metal-encapsulated biphenylene bilayers, B/M/B, with M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Ru, W, Os and Pt. In most systems, the intercalated metal sits at the square carbon sites (C468) of the biphenylene lattice. Using a computational hydrogen electrode approach, we evaluated the reaction energetics at these active sites. Several B/M/B systems show competitive ORR and OER performance. Among the investigated systems, Cu, Pt, Ru, and Mn exhibit the lowest ORR overpotentials of 0.42, 0.44, 0.50, and 0.56 V, respectively, while Fe is identified as the most active catalyst for OER with an overpotential of 0.44 V. To understand the catalytic trends, we looked at the electronic structure through the metal d−band centers, the C468 pz−band centers, and the corresponding orbital charge populations. The band centers did not give a simple polynomial dependence on the overpotentials, though they did point to favorable electronic ranges for the best catalysts. The d−orbital charge population of the encapsulated metal, however, correlated most clearly with activity-especially for OER-yielding volcano-type plots. From these, B/Fe/B emerges as the best OER catalyst, while B/Mn/B lies closest to the ORR optimum. The p−orbital population at the active carbon site also captures the main trends, albeit less strongly. Overall, these results show that straightforward electronic descriptors can predict catalytic behavior in metal-encapsulated biphenylene bilayers and guide the search for efficient catalysts where the carbon framework itself drives the reactivity.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
We conducted an {it ab initio} study of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in metal-encapsulated biphenylene bilayers, B/M/B, with M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Ru, W, Os and Pt. In most systems, the intercalated metal sits at the square carbon sites (C468) of the biphenylene lattice. Using a computational hydrogen electrode approach, we evaluated the reaction energetics at these active sites. Several B/M/B systems show competitive ORR and OER performance. Among the investigated systems, Cu, Pt, Ru, and Mn exhibit the lowest ORR overpotentials of 0.42, 0.44, 0.50, and 0.56 V, respectively, while Fe is identified as the most active catalyst for OER with an overpotential of 0.44 V. To understand the catalytic trends, we looked at the electronic structure through the metal d−band centers, the C468 pz−band centers, and the corresponding orbital charge populations. The band centers did not give a simple polynomial dependence on the overpotentials, though they did point to favorable electronic ranges for the best catalysts. The d−orbital charge population of the encapsulated metal, however, correlated most clearly with activity-especially for OER-yielding volcano-type plots. From these, B/Fe/B emerges as the best OER catalyst, while B/Mn/B lies closest to the ORR optimum. The p−orbital population at the active carbon site also captures the main trends, albeit less strongly. Overall, these results show that straightforward electronic descriptors can predict catalytic behavior in metal-encapsulated biphenylene bilayers and guide the search for efficient catalysts where the carbon framework itself drives the reactivity.
Conceição, Victor M. S.; Lima, Erika N.; Miwa, Roberto H.; Oliveira, Igor S. S.
Beyond Hexagonal Boron Nitride: First-Principles Study of Pentaoctite-BN and Pop-BN Monolayers Miscellaneous
2026.
@misc{daconceição2026hexagonalboronnitridefirstprinciples,
title = {Beyond Hexagonal Boron Nitride: First-Principles Study of Pentaoctite-BN and Pop-BN Monolayers},
author = {Victor M. S. Conceição and Erika N. Lima and Roberto H. Miwa and Igor S. S. Oliveira},
url = {https://arxiv.org/abs/2607.27554},
year = {2026},
date = {2026-07-30},
urldate = {2026-01-01},
abstract = {We investigate two novel non-hexagonal boron nitride monolayers, pentaoctite-BN (PO-BN) and pop-BN (PP-BN), using first-principles calculations. Their structural, electronic, mechanical, vibrational, thermal, and optical properties are systematically analyzed to assess their stability and potential applications. Despite being metastable with respect to hexagonal BN, both polymorphs satisfy the criteria for dynamical, mechanical, and thermal stability, indicating that they are viable two-dimensional materials. Both systems are indirect-gap semiconductors whose electronic states near the band edges are dominated by out-of-plane pz orbitals. Their distinct pentagon-octagon ring networks also give rise to different in-plane elastic anisotropies. Many-body optical calculations reveal strong excitonic effects and pronounced polarization-dependent optical absorption, with lattice engineering shifting the optical response from the ultraviolet toward the visible and infrared regions. These findings demonstrate that engineering non-hexagonal lattice architectures provides an effective strategy for tuning the electronic and optical properties of two-dimensional BN, highlighting PO-BN and PP-BN as promising candidates for future optoelectronic and photonic applications.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
We investigate two novel non-hexagonal boron nitride monolayers, pentaoctite-BN (PO-BN) and pop-BN (PP-BN), using first-principles calculations. Their structural, electronic, mechanical, vibrational, thermal, and optical properties are systematically analyzed to assess their stability and potential applications. Despite being metastable with respect to hexagonal BN, both polymorphs satisfy the criteria for dynamical, mechanical, and thermal stability, indicating that they are viable two-dimensional materials. Both systems are indirect-gap semiconductors whose electronic states near the band edges are dominated by out-of-plane pz orbitals. Their distinct pentagon-octagon ring networks also give rise to different in-plane elastic anisotropies. Many-body optical calculations reveal strong excitonic effects and pronounced polarization-dependent optical absorption, with lattice engineering shifting the optical response from the ultraviolet toward the visible and infrared regions. These findings demonstrate that engineering non-hexagonal lattice architectures provides an effective strategy for tuning the electronic and optical properties of two-dimensional BN, highlighting PO-BN and PP-BN as promising candidates for future optoelectronic and photonic applications.
Sousa, Lucas Soares; Lima, Felipe Crasto; Miwa, Roberto Hiroki
Tunable Electronic and Transport Properties of Biphenylene via Fluorination and Disorder Miscellaneous
2026.
@misc{sousa2026tunableelectronictransportproperties,
title = {Tunable Electronic and Transport Properties of Biphenylene via Fluorination and Disorder},
author = {Lucas Soares Sousa and Felipe Crasto Lima and Roberto Hiroki Miwa},
url = {https://arxiv.org/abs/2606.18083},
year = {2026},
date = {2026-06-16},
urldate = {2026-01-01},
abstract = {Biphenylene (BPN) network is a newly synthesized 2D carbon allotrope hosting anisotropic Dirac electronic states. Here, we investigate how fluorination and correlated chemical disorder modify the electronic structure and charge transport of fluorinated biphenylene (F/BPN) using density functional theory, Wannier-based tight-biding Hamiltonian, and quantum transport simulations. We show that fluorination reshapes the transport response of BPN, producing concentration-dependent anisotropic conduction regimes. For pristine and ordered fluorinated systems, we identified the emergence of negative differential resistance (NDR) and a bias-induced inversion of the preferred transport direction, from armchair to zigzag and vice versa. In contrast, disorder suppresses the NDR, driving the system toward an approximately Ohmic transport regime. At high fluorine coverage, we further observed a nonmonotonic dependence of the armchair current on adatom concentration, which we attribute to the formation of correlated quasi-linear fluor conformation that promote armchair-oriented C- transport channels while simultaneously suppressing transport along the zigzag direction. Our results demonstrate that correlated fluorination can be used as an active mechanism to engineer electronic transport.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
Biphenylene (BPN) network is a newly synthesized 2D carbon allotrope hosting anisotropic Dirac electronic states. Here, we investigate how fluorination and correlated chemical disorder modify the electronic structure and charge transport of fluorinated biphenylene (F/BPN) using density functional theory, Wannier-based tight-biding Hamiltonian, and quantum transport simulations. We show that fluorination reshapes the transport response of BPN, producing concentration-dependent anisotropic conduction regimes. For pristine and ordered fluorinated systems, we identified the emergence of negative differential resistance (NDR) and a bias-induced inversion of the preferred transport direction, from armchair to zigzag and vice versa. In contrast, disorder suppresses the NDR, driving the system toward an approximately Ohmic transport regime. At high fluorine coverage, we further observed a nonmonotonic dependence of the armchair current on adatom concentration, which we attribute to the formation of correlated quasi-linear fluor conformation that promote armchair-oriented C- transport channels while simultaneously suppressing transport along the zigzag direction. Our results demonstrate that correlated fluorination can be used as an active mechanism to engineer electronic transport.
Miwa, Roberto H.; Kuritza, Danilo P.; Padilha, José E.; Freire, Rafael L. H.; Lima, Felipe Crasto; Fazzio, Adalberto
Thickness-Dependent Electronic and Transport Properties of PtSe _2 on Au(111) Journal Article
Em: J. Phys. Chem. C, 2026, ISSN: 1932-7455.
@article{Miwa2026,
title = {Thickness-Dependent Electronic and Transport Properties of PtSe _2 on Au(111)},
author = {Roberto H. Miwa and Danilo P. Kuritza and José E. Padilha and Rafael L. H. Freire and Felipe Crasto Lima and Adalberto Fazzio},
doi = {10.1021/acs.jpcc.5c07502},
issn = {1932-7455},
year = {2026},
date = {2026-04-16},
urldate = {2026-04-16},
journal = {J. Phys. Chem. C},
publisher = {American Chemical Society (ACS)},
abstract = {Among two-dimensional materials, platinum diselenide (PtSe2) has attracted interest for applications in electronic devices such as transistors and sensors, mainly due to the thickness dependence of its bandgap. Thus, understanding electronic confinement and transport properties in contact with metals is essential for device design. Here, using density functional theory, we investigated the structural, electronic, and electronic transport properties of monolayer (ML), bilayer (BL), and trilayer (TL) PtSe2 on Au(111), PtSe2-X/Au (X = ML, BL, TL). We find the emergence of a chemical interaction at the interface, leading to (i) ohmic contact, (ii) hole doping of PtSe2, and (iii) metallization of the contact layer. In PtSe2-ML/Au, the semiconductor ML becomes metallic, while in PtSe2–BL/Au and PtSe2-TL/Au, the top layers, which do not directly contact Au, become semimetallic. Transport calculations further reveal a thickness-dependent behavior of the electronic transmittance and Schottky barriers along the PtSe2-X channels in contact with the PtSe2-X/Au(111) leads. Based on this atomistic understanding, we propose a heterostructure, Au/PtSe2-TL/Au, where a metal–semiconductor transition can be tuned by mechanical strain. These results highlight the potential of few-layer PtSe2 for two-dimensional electronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Among two-dimensional materials, platinum diselenide (PtSe2) has attracted interest for applications in electronic devices such as transistors and sensors, mainly due to the thickness dependence of its bandgap. Thus, understanding electronic confinement and transport properties in contact with metals is essential for device design. Here, using density functional theory, we investigated the structural, electronic, and electronic transport properties of monolayer (ML), bilayer (BL), and trilayer (TL) PtSe2 on Au(111), PtSe2-X/Au (X = ML, BL, TL). We find the emergence of a chemical interaction at the interface, leading to (i) ohmic contact, (ii) hole doping of PtSe2, and (iii) metallization of the contact layer. In PtSe2-ML/Au, the semiconductor ML becomes metallic, while in PtSe2–BL/Au and PtSe2-TL/Au, the top layers, which do not directly contact Au, become semimetallic. Transport calculations further reveal a thickness-dependent behavior of the electronic transmittance and Schottky barriers along the PtSe2-X channels in contact with the PtSe2-X/Au(111) leads. Based on this atomistic understanding, we propose a heterostructure, Au/PtSe2-TL/Au, where a metal–semiconductor transition can be tuned by mechanical strain. These results highlight the potential of few-layer PtSe2 for two-dimensional electronic devices.
Pereira, Gabriel X.; Farigliano, Lucas M.; Miwa, Roberto H.; Dalpian, Gustavo M.
Intrinsic Instabilities and Mechanical Anisotropy in Halide Perovskite Monolayers Miscellaneous
2026.
@misc{pereira2026intrinsicinstabilitiesmechanicalanisotropy,
title = {Intrinsic Instabilities and Mechanical Anisotropy in Halide Perovskite Monolayers},
author = {Gabriel X. Pereira and Lucas M. Farigliano and Roberto H. Miwa and Gustavo M. Dalpian},
url = {https://arxiv.org/abs/2602.21989},
year = {2026},
date = {2026-02-25},
urldate = {2026-02-25},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
Pereira, Gabriel X.; Farigliano, Lucas M.; Miwa, Roberto H.; Dalpian, Gustavo M.
Intrinsic Instabilities and Mechanical Anisotropy in Halide Perovskite Monolayers Miscellaneous
2026.
@misc{pereira2026intrinsicinstabilitiesmechanicalanisotropyb,
title = {Intrinsic Instabilities and Mechanical Anisotropy in Halide Perovskite Monolayers},
author = {Gabriel X. Pereira and Lucas M. Farigliano and Roberto H. Miwa and Gustavo M. Dalpian},
url = {https://arxiv.org/abs/2602.21989},
year = {2026},
date = {2026-02-25},
urldate = {2026-01-01},
abstract = {Halide perovskites have been extensively studied owing to their excellent optoelectronic properties and their unique lattice characteristics, that are very soft and anharmonic. Recent studies indicate the importance of a deep understanding of their surfaces and, in the limit, the properties of low-dimensional structures based on these materials. To investigate the structural and electronic properties of halide perovskite monolayers (i.e., perovskenes), this work uses first-principles simulations. We have studied three different stoichiometries (ABX3, ABX4, and A2BX4) and structural phases for iodide, bromide, and chloride perovskite monolayers. Their thermodynamic behavior was evaluated through the construction of phase diagrams, highlighting the instability of the ABX4 stoichiometry, which was further supported by its mechanical instability. Structurally, the covalent characteristics of the Pb–X bond, in contrast to the Cs–X bonds, induce a strong anisotropy in the Young's modulus and Poisson's ratio along different crystallographic directions, and also account for the lower stiffness observed in the phases where the octahedra are not aligned. The electronic properties are somewhat similar to those of their 3D counterparts, but with a slightly larger band gap; in the monolayers, the band gap increases with halogen electronegativity (I, Br, Cl) and octahedral tilting. Moreover, the non-symmetric ABX3 stoichiometry exhibited a spin splitting due to the internal dipole moment in these layers. Overall, our work lays the groundwork for a deeper understanding of low-dimensional structures based on halide perovskites.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
Halide perovskites have been extensively studied owing to their excellent optoelectronic properties and their unique lattice characteristics, that are very soft and anharmonic. Recent studies indicate the importance of a deep understanding of their surfaces and, in the limit, the properties of low-dimensional structures based on these materials. To investigate the structural and electronic properties of halide perovskite monolayers (i.e., perovskenes), this work uses first-principles simulations. We have studied three different stoichiometries (ABX3, ABX4, and A2BX4) and structural phases for iodide, bromide, and chloride perovskite monolayers. Their thermodynamic behavior was evaluated through the construction of phase diagrams, highlighting the instability of the ABX4 stoichiometry, which was further supported by its mechanical instability. Structurally, the covalent characteristics of the Pb–X bond, in contrast to the Cs–X bonds, induce a strong anisotropy in the Young's modulus and Poisson's ratio along different crystallographic directions, and also account for the lower stiffness observed in the phases where the octahedra are not aligned. The electronic properties are somewhat similar to those of their 3D counterparts, but with a slightly larger band gap; in the monolayers, the band gap increases with halogen electronegativity (I, Br, Cl) and octahedral tilting. Moreover, the non-symmetric ABX3 stoichiometry exhibited a spin splitting due to the internal dipole moment in these layers. Overall, our work lays the groundwork for a deeper understanding of low-dimensional structures based on halide perovskites.
2025
Piero, João V B Del; Miwa, Roberto H.; Scopel, Wanderlã L.
Vanadium incorporation in 2D-layered MoSe2 Journal Article
Em: J. Phys.: Condens. Matter, vol. 37, não 4, 2025, ISSN: 1361-648X.
@article{DelPiero2024,
title = {Vanadium incorporation in 2D-layered MoSe2},
author = {João V B Del Piero and Roberto H. Miwa and Wanderlã L. Scopel},
url = {https://iopscience.iop.org/article/10.1088/1361-648X/ad8abb/meta},
doi = {10.1088/1361-648x/ad8abb},
issn = {1361-648X},
year = {2025},
date = {2025-11-11},
urldate = {2025-01-27},
journal = {J. Phys.: Condens. Matter},
volume = {37},
number = {4},
publisher = {IOP Publishing},
abstract = {Recent advances in experimental techniques have made it possible to manipulate the structural and electronic properties of two-dimensional layered materials (2DM) through interaction with foreign atoms. Using quantum mechanics calculations based on the density functional theory, we explored the dependency of the structural, energetic, electronic, and magnetic properties of the interaction between Vanadium (V) atoms and monolayer and bilayer MoSe2. Spin-polarized metallic behavior was observed for high V concentration, and a semiconductor/metal interface emerged due to V adsorption on top of BL MoSe2. Our research demonstrated that the functionalization of 2D materials makes an important contribution to the design of spintronic devices based on a 2D-layered materials platform.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recent advances in experimental techniques have made it possible to manipulate the structural and electronic properties of two-dimensional layered materials (2DM) through interaction with foreign atoms. Using quantum mechanics calculations based on the density functional theory, we explored the dependency of the structural, energetic, electronic, and magnetic properties of the interaction between Vanadium (V) atoms and monolayer and bilayer MoSe2. Spin-polarized metallic behavior was observed for high V concentration, and a semiconductor/metal interface emerged due to V adsorption on top of BL MoSe2. Our research demonstrated that the functionalization of 2D materials makes an important contribution to the design of spintronic devices based on a 2D-layered materials platform.
Quintero, Leonardo; Miwa, R. H.; Franca, J. R.; Acuña, Jose J. S.; Dalpian, G. M.; Souza, Jose A.
Em: vol. 138, não 12, 2025, ISSN: 1089-7550.
@article{Quintero2025,
title = {Comprehensive experimental and theoretical study on the interaction between Ag nanoparticles and all-inorganic CsPb(Br,I)3 perovskite nanocrystals},
author = {Leonardo Quintero and R. H. Miwa and J. R. Franca and Jose J. S. Acuña and G. M. Dalpian and Jose A. Souza},
doi = {10.1063/5.0288333},
issn = {1089-7550},
year = {2025},
date = {2025-09-28},
urldate = {2025-09-28},
volume = {138},
number = {12},
publisher = {AIP Publishing},
abstract = {<jats:p>The energy conversion efficiency in halide perovskites remains limited by charge carrier generation, separation, mobility, and extraction. In this work, we investigate interfacial interactions governing exciton dynamics in all-inorganic CsPb(Br,I)3 nanocrystals coupled with Ag metallic nanoparticles (AgNPs). Our findings reveal strong photoluminescence (PL) quenching when AgNPs are deposited on the surface of CsPb(Br,I)3 nanocrystals, indicating the charge transfer process. A comprehensive theoretical analysis suggests that the interaction between CsX-terminated quantum dots (QDs) and AgNPs is primarily governed by weak physical adsorption van der Waals (vdW) forces, which is in contrast to PbX2 terminations, where the QD/NP interface is mediated by a combination of vdW forces and stronger chemical interactions. Our electronic structure calculations confirm the feasibility of carrier separation and the emergence of two concurrent charging processes at the QD/NP interfaces. The final charge separation configuration of QD[h]/NP[e], meaning that holes are localized in the QDs and the electrons at the nanoparticles, is more likely to occur than QD[e]/NP[h]. We discuss the electron–hole creation and separation mechanisms at the heterostructure interface, highlighting how enhanced interfacial interactions improve electronic coupling, influence optical response, and modify charge carrier dynamics. Understanding these interfacial mechanisms is essential for optimizing perovskite-based nanostructures in optoelectronics applications.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>The energy conversion efficiency in halide perovskites remains limited by charge carrier generation, separation, mobility, and extraction. In this work, we investigate interfacial interactions governing exciton dynamics in all-inorganic CsPb(Br,I)3 nanocrystals coupled with Ag metallic nanoparticles (AgNPs). Our findings reveal strong photoluminescence (PL) quenching when AgNPs are deposited on the surface of CsPb(Br,I)3 nanocrystals, indicating the charge transfer process. A comprehensive theoretical analysis suggests that the interaction between CsX-terminated quantum dots (QDs) and AgNPs is primarily governed by weak physical adsorption van der Waals (vdW) forces, which is in contrast to PbX2 terminations, where the QD/NP interface is mediated by a combination of vdW forces and stronger chemical interactions. Our electronic structure calculations confirm the feasibility of carrier separation and the emergence of two concurrent charging processes at the QD/NP interfaces. The final charge separation configuration of QD[h]/NP[e], meaning that holes are localized in the QDs and the electrons at the nanoparticles, is more likely to occur than QD[e]/NP[h]. We discuss the electron–hole creation and separation mechanisms at the heterostructure interface, highlighting how enhanced interfacial interactions improve electronic coupling, influence optical response, and modify charge carrier dynamics. Understanding these interfacial mechanisms is essential for optimizing perovskite-based nanostructures in optoelectronics applications.</jats:p>
DesRoche, Emmett; Lima, Felipe Crasto; Groome, Ryan R. K.; Furlan, Michael; Tumino, Francesco; Inayeh, Alex; Aloisio, Mark D.; Singh, Ishwar; Veinot, Alex J.; Miwa, Roberto H.; Crudden, Cathleen M.; McLean, Alastair B.
Mechanisms of N-Heterocyclic Carbene Complex Lattice Formation Journal Article
Em: ACS Nano, 2025, ISSN: 1936-086X.
@article{DesRoche2025,
title = {Mechanisms of N-Heterocyclic Carbene Complex Lattice Formation},
author = {Emmett DesRoche and Felipe Crasto Lima and Ryan R. K. Groome and Michael Furlan and Francesco Tumino and Alex Inayeh and Mark D. Aloisio and Ishwar Singh and Alex J. Veinot and Roberto H. Miwa and Cathleen M. Crudden and Alastair B. McLean},
doi = {10.1021/acsnano.5c06139},
issn = {1936-086X},
year = {2025},
date = {2025-08-25},
urldate = {2025-08-25},
journal = {ACS Nano},
publisher = {American Chemical Society (ACS)},
abstract = {N-Heterocyclic carbenes (NHCs) that have wingtip groups with low steric bulk, such as 1,3-dimethyl-benzimidazol-2-ylidene (NHCMe), form bis-complexes with metal atoms when they are deposited onto Au(111) surfaces in vacuo. These complexes self-assemble into three different lattices: a herringbone, a double-herringbone, and a chiral kagome lattice. The static properties of these lattices have been studied with scanning tunneling microscopy and ab initio theoretical methods. Dynamic processes including complex center displacement and hindered monomer motion have also been observed. Our results suggest that in addition to surface hopping, exchange processes are important, providing a facile mechanism for atom exchange between the overlayer and the metal. These dynamic processes are well-known from studies of metal epitaxy but have not previously been discussed in the context of NHC self-assembly.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
N-Heterocyclic carbenes (NHCs) that have wingtip groups with low steric bulk, such as 1,3-dimethyl-benzimidazol-2-ylidene (NHCMe), form bis-complexes with metal atoms when they are deposited onto Au(111) surfaces in vacuo. These complexes self-assemble into three different lattices: a herringbone, a double-herringbone, and a chiral kagome lattice. The static properties of these lattices have been studied with scanning tunneling microscopy and ab initio theoretical methods. Dynamic processes including complex center displacement and hindered monomer motion have also been observed. Our results suggest that in addition to surface hopping, exchange processes are important, providing a facile mechanism for atom exchange between the overlayer and the metal. These dynamic processes are well-known from studies of metal epitaxy but have not previously been discussed in the context of NHC self-assembly.
Vidarte, Kevin J. U.; Lewenkopf, Caio; Lima, F. Crasto; Miwa, R. Hiroki; Riffo, Felipe Pérez; Morell, Eric Suárez
Unveiling the Electronic Origin of Anomalous Contact Conductance in Twisted Bilayer Graphene Miscellaneous
2025.
@misc{vidarte2025unveilingelectronicoriginanomalous,
title = {Unveiling the Electronic Origin of Anomalous Contact Conductance in Twisted Bilayer Graphene},
author = {Kevin J. U. Vidarte and Caio Lewenkopf and F. Crasto Lima and R. Hiroki Miwa and Felipe Pérez Riffo and Eric Suárez Morell},
url = {https://arxiv.org/abs/2506.21721},
year = {2025},
date = {2025-06-26},
urldate = {2025-01-01},
abstract = {This study theoretically investigates the contact conductance in twisted bilayer graphene (TBG), providing a theoretical explanation for recent experimental observations from scanning tunneling microscopy (STM) and conductive atomic force microscopy (c-AFM). These experiments revealed a surprising non-monotonic current pattern as a function of the TBG rotation angle θ, with a peak at θ ≈ 5 ◦, a finding that markedly departs from the well-known magic angle TBG behavior. To elucidate this phenomenon, we develop a comprehensive theoretical and computational framework. Our calculations, performed on both relaxed and rigid TBG structures, simulate contact conductance by analyzing the local density of states across a range of biases and rotational angles. Contrary to the current interpretation, our results demonstrate that the maximum conductance at θ ≈ 5 o is not caused by structural relaxation or AA stacking zone changes. Instead, we attribute this peak
to the evolution of the electronic band structure, specifically the shifting of van Hove singularities (vHs) to the Fermi level as the twist angle decreases. We further show that the precise location of this conductance maximum is dependent on the applied bias voltage. This interplay between twist angle, bias, and vHs energy provides a robust explanation for the experimental findings.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
This study theoretically investigates the contact conductance in twisted bilayer graphene (TBG), providing a theoretical explanation for recent experimental observations from scanning tunneling microscopy (STM) and conductive atomic force microscopy (c-AFM). These experiments revealed a surprising non-monotonic current pattern as a function of the TBG rotation angle θ, with a peak at θ ≈ 5 ◦, a finding that markedly departs from the well-known magic angle TBG behavior. To elucidate this phenomenon, we develop a comprehensive theoretical and computational framework. Our calculations, performed on both relaxed and rigid TBG structures, simulate contact conductance by analyzing the local density of states across a range of biases and rotational angles. Contrary to the current interpretation, our results demonstrate that the maximum conductance at θ ≈ 5 o is not caused by structural relaxation or AA stacking zone changes. Instead, we attribute this peak
to the evolution of the electronic band structure, specifically the shifting of van Hove singularities (vHs) to the Fermi level as the twist angle decreases. We further show that the precise location of this conductance maximum is dependent on the applied bias voltage. This interplay between twist angle, bias, and vHs energy provides a robust explanation for the experimental findings.
to the evolution of the electronic band structure, specifically the shifting of van Hove singularities (vHs) to the Fermi level as the twist angle decreases. We further show that the precise location of this conductance maximum is dependent on the applied bias voltage. This interplay between twist angle, bias, and vHs energy provides a robust explanation for the experimental findings.
Dias, Victor M. S. C.; Kuritza, Danilo P.; Oliveira, Igor S. S.; Padilha, José E.; Miwa, R. H.
Catenary-like Rippled Biphenylene/Graphene Lateral Heterojunction Journal Article
Em: J. Phys. Chem. C, 2025, ISSN: 1932-7455.
@article{daC.Dias2025,
title = {Catenary-like Rippled Biphenylene/Graphene Lateral Heterojunction},
author = {Victor M. S. C. Dias and Danilo P. Kuritza and Igor S. S. Oliveira and José E. Padilha and R. H. Miwa},
doi = {10.1021/acs.jpcc.5c01823},
issn = {1932-7455},
year = {2025},
date = {2025-06-18},
urldate = {2025-06-18},
journal = {J. Phys. Chem. C},
publisher = {American Chemical Society (ACS)},
abstract = {In this study, we conduct a first-principles analysis to explore the structural and electronic properties of curved biphenylene/graphene lateral junctions (BPN/G). We started our investigation focusing on the energetic stability of BPN/G by varying the width of the graphene region, BPN/G. The electronic structure of BPN/G reveals (i) the formation of metallic channels mostly localized along the BPN stripes, where (ii) the features of the energy bands near the Fermi level are ruled by the width (n) of the graphene regions, G. In the sequence, we find that the hydrogenation of BPN/G results in a semiconductor system with a catenary-like rippled geometry. The electronic states of the hydrogenated system are mainly confined in the curved G regions, and the dependence of the bandgap on the width of G is similar to that of hydrogenated armchair graphene nanoribbons. The effects of curvature on the electronic structure, analyzed in terms of external mechanical strain, revealed that the increase or decrease of the band gap is also dictated by the width of the G region. Further electronic transport calculations reveal a combination of strong transmission anisotropy and the emergence of negative differential resistance. Based on these findings, we believe that rippled biphenylene/graphene systems can be useful for the design of two-dimensional nanodevices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, we conduct a first-principles analysis to explore the structural and electronic properties of curved biphenylene/graphene lateral junctions (BPN/G). We started our investigation focusing on the energetic stability of BPN/G by varying the width of the graphene region, BPN/G. The electronic structure of BPN/G reveals (i) the formation of metallic channels mostly localized along the BPN stripes, where (ii) the features of the energy bands near the Fermi level are ruled by the width (n) of the graphene regions, G. In the sequence, we find that the hydrogenation of BPN/G results in a semiconductor system with a catenary-like rippled geometry. The electronic states of the hydrogenated system are mainly confined in the curved G regions, and the dependence of the bandgap on the width of G is similar to that of hydrogenated armchair graphene nanoribbons. The effects of curvature on the electronic structure, analyzed in terms of external mechanical strain, revealed that the increase or decrease of the band gap is also dictated by the width of the G region. Further electronic transport calculations reveal a combination of strong transmission anisotropy and the emergence of negative differential resistance. Based on these findings, we believe that rippled biphenylene/graphene systems can be useful for the design of two-dimensional nanodevices.
Lima, F. Crasto; Miwa, Roberto H.; Lewenkopf, Caio; Fazzio, Adalberto
Interacting virtual topological phases in defect-rich two-dimensional materials Journal Article
Em: Phys. Rev. B, vol. 111, não 19, 2025, ISSN: 2469-9969.
@article{deLima2025,
title = {Interacting virtual topological phases in defect-rich two-dimensional materials},
author = {F. Crasto Lima and Roberto H. Miwa and Caio Lewenkopf and Adalberto Fazzio},
doi = {10.1103/physrevb.111.195135},
issn = {2469-9969},
year = {2025},
date = {2025-05-19},
journal = {Phys. Rev. B},
volume = {111},
number = {19},
publisher = {American Physical Society (APS)},
abstract = {We investigate the robustness of virtual topological states—topological phases away from the Fermi energy—against the electron-electron interaction and band filling. As a case study, we employ a realistic model to investigate the properties of vacancy-driven topological phases in transition metal dichalcogenides (TMDs) and establish a connection between the degree of localization of topological wave functions, the vacancy density, and the electron-electron interaction strength with the topological phase robustness. We demonstrate that electron-electron interactions play a crucial role in degrading topological phases thereby determining the validity of single-particle approximations for topological insulator phases. Our findings can be naturally extended to virtual topological phases of a wide range of materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We investigate the robustness of virtual topological states—topological phases away from the Fermi energy—against the electron-electron interaction and band filling. As a case study, we employ a realistic model to investigate the properties of vacancy-driven topological phases in transition metal dichalcogenides (TMDs) and establish a connection between the degree of localization of topological wave functions, the vacancy density, and the electron-electron interaction strength with the topological phase robustness. We demonstrate that electron-electron interactions play a crucial role in degrading topological phases thereby determining the validity of single-particle approximations for topological insulator phases. Our findings can be naturally extended to virtual topological phases of a wide range of materials.
Souza, Pedro H.; Padilha, José E.; Miwa, R. H.
Spin-polarized nearly-free electron channels on fluorinated <mml:math xmlns:mml= Journal Article
Em: Phys. Rev. Materials, vol. 9, não 5, 2025, ISSN: 2475-9953.
@article{Souza2025,
title = {Spin-polarized nearly-free electron channels on fluorinated <mml:math xmlns:mml=},
author = {Pedro H. Souza and José E. Padilha and R. H. Miwa},
doi = {10.1103/physrevmaterials.9.054001},
issn = {2475-9953},
year = {2025},
date = {2025-05-01},
journal = {Phys. Rev. Materials},
volume = {9},
number = {5},
publisher = {American Physical Society (APS)},
abstract = {Two-dimensional (2D) materials combined with surface nearly free electrons (NFE) have been considered quite interesting platforms to be exploited for the development of 2D electronic devices. Further incorporation of foreign elements adds a new degree of freedom to engineer both the electronic and magnetic properties of 2D materials. Here, we have performed an ab initio study of Ca2N electrenes fully (i.e., both sides) adsorbed by fluorine (F/Ca2N/F) atoms. The NFE states are suppressed in these systems, followed by the appearance of a net magnetic moment localized in the nitrogen atoms intercalated by the fluorinated calcium layers. In the sequence, we have proposed lateral heterostructures combining F/Ca2N/F regions with pristine Ca2N electrenes [(Ca2N)(F/Ca2N/F)]. We found that the magnetic moment of the fluorinated regions promotes the emergence of spin-polarized NFE states confined along the pristine (Ca2N) stripes. Further electronic transport calculations reveal that the (F/Ca2N/F) regions act as spin-dependent scattering centers, or spin filter. We believe that these findings make an important contribution to the development of spintronic devices based on 2D electrides.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Two-dimensional (2D) materials combined with surface nearly free electrons (NFE) have been considered quite interesting platforms to be exploited for the development of 2D electronic devices. Further incorporation of foreign elements adds a new degree of freedom to engineer both the electronic and magnetic properties of 2D materials. Here, we have performed an ab initio study of Ca2N electrenes fully (i.e., both sides) adsorbed by fluorine (F/Ca2N/F) atoms. The NFE states are suppressed in these systems, followed by the appearance of a net magnetic moment localized in the nitrogen atoms intercalated by the fluorinated calcium layers. In the sequence, we have proposed lateral heterostructures combining F/Ca2N/F regions with pristine Ca2N electrenes [(Ca2N)(F/Ca2N/F)]. We found that the magnetic moment of the fluorinated regions promotes the emergence of spin-polarized NFE states confined along the pristine (Ca2N) stripes. Further electronic transport calculations reveal that the (F/Ca2N/F) regions act as spin-dependent scattering centers, or spin filter. We believe that these findings make an important contribution to the development of spintronic devices based on 2D electrides.
Lima, F. Crasto; Miwa, Roberto H.; Lewenkopf, Caio; Fazzio, Adalberto
Interacting virtual topological phases in defect-rich two-dimensional materials Journal Article
Em: Phys. Rev. B, vol. 111, não 19, 2025, ISSN: 2469-9969.
@article{deLima2025b,
title = {Interacting virtual topological phases in defect-rich two-dimensional materials},
author = {F. Crasto Lima and Roberto H. Miwa and Caio Lewenkopf and Adalberto Fazzio},
doi = {10.1103/physrevb.111.195135},
issn = {2469-9969},
year = {2025},
date = {2025-05-01},
journal = {Phys. Rev. B},
volume = {111},
number = {19},
publisher = {American Physical Society (APS)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Dias, Victor M. S. C.; Kuritza, Danilo P.; Oliveira, Igor S. S.; Padilha, Jose E.; Miwa, Roberto H.
Catenary-like rippled biphenylene/graphene lateral heterojunction Working paper
2025.
@workingpaper{dias2025catenarylikerippledbiphenylenegraphenelateral,
title = {Catenary-like rippled biphenylene/graphene lateral heterojunction},
author = {Victor M. S. C. Dias and Danilo P. Kuritza and Igor S. S. Oliveira and Jose E. Padilha and Roberto H. Miwa},
url = {https://arxiv.org/abs/2503.07816},
doi = {https://doi.org/10.48550/arXiv.2503.07816},
year = {2025},
date = {2025-03-10},
urldate = {2025-01-01},
abstract = {In this study, we conduct a first-principles analysis to explore the structural and electronic properties of curved biphenylene/graphene lateral junctions (BPN/G). We start our investigation focusing on the energetic stability of BPN/G by varying the width of the graphene region, BPN/Gn. The electronic structure of BPN/Gn reveals (i) the formation of metallic channels mostly localized along the BPN stripes, where (ii) the features of the energy bands near the Fermi level are ruled by the width (n) of the graphene regions, Gn. In the sequence, we find that the hydrogenation of BPN/Gn results in a semiconductor system with a catenary-like rippled geometry. The electronic states of the hydrogenated system are mainly confined in the curved Gn regions, and the dependence of the bandgap on the width of Gn is similar to that of hydrogenated armchair graphene nanoribbons. The effects of curvature on the electronic structure, analyzed in terms of external mechanical strain, revealed that the increase/decrease of the band gap is also dictated by the width of the Gn region. Further electronic transport calculations reveal a combination of strong transmission anisotropy and the emergence of negative differential resistance. Based on these findings, we believe that rippled biphenylene/graphene systems can be useful for the design of two-dimensional nanodevices.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
In this study, we conduct a first-principles analysis to explore the structural and electronic properties of curved biphenylene/graphene lateral junctions (BPN/G). We start our investigation focusing on the energetic stability of BPN/G by varying the width of the graphene region, BPN/Gn. The electronic structure of BPN/Gn reveals (i) the formation of metallic channels mostly localized along the BPN stripes, where (ii) the features of the energy bands near the Fermi level are ruled by the width (n) of the graphene regions, Gn. In the sequence, we find that the hydrogenation of BPN/Gn results in a semiconductor system with a catenary-like rippled geometry. The electronic states of the hydrogenated system are mainly confined in the curved Gn regions, and the dependence of the bandgap on the width of Gn is similar to that of hydrogenated armchair graphene nanoribbons. The effects of curvature on the electronic structure, analyzed in terms of external mechanical strain, revealed that the increase/decrease of the band gap is also dictated by the width of the Gn region. Further electronic transport calculations reveal a combination of strong transmission anisotropy and the emergence of negative differential resistance. Based on these findings, we believe that rippled biphenylene/graphene systems can be useful for the design of two-dimensional nanodevices.
Silvestre, G. H.; Miwa, Roberto H.
TCNQ self-assembly driven by molecular coverage over borophene monolayers Miscellaneous
2025.
@misc{silvestre2025tcnqselfassemblydrivenmolecular,
title = {TCNQ self-assembly driven by molecular coverage over borophene monolayers},
author = {G. H. Silvestre and Roberto H. Miwa},
url = {https://arxiv.org/abs/2504.01238},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
2024
Lima, F. Crasto; Miwa, Roberto H.; Lewenkopf, Caio; Fazzio, Adalberto
Interacting Virtual Topological Phases in Defect-Rich 2D Materials Working paper
2024.
@workingpaper{delima2024interactingvirtualtopologicalphases,
title = {Interacting Virtual Topological Phases in Defect-Rich 2D Materials},
author = {F. Crasto Lima and Roberto H. Miwa and Caio Lewenkopf and Adalberto Fazzio},
url = {https://arxiv.org/abs/2412.08607},
year = {2024},
date = {2024-12-11},
urldate = {2024-01-01},
abstract = {We investigate the robustness of it virtual topological states – topological phases away from the Fermi energy – against the electron-electron interaction and band filling. As a case study, we employ a realistic model to investigate the properties of vacancy-driven topological phases in transition metal dichalcogenides (TMDs) and establish a connection between the degree of localization of topological wave functions, the vacancy density, and the electron-electron interaction strength with the topological phase robustness. We demonstrate that electron-electron interactions play a crucial role in degrading topological phases thereby determining the validity of single-particle approximations for topological insulator phases. Our findings can be naturally extended to virtual topological phases of a wide range of materials.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
We investigate the robustness of it virtual topological states – topological phases away from the Fermi energy – against the electron-electron interaction and band filling. As a case study, we employ a realistic model to investigate the properties of vacancy-driven topological phases in transition metal dichalcogenides (TMDs) and establish a connection between the degree of localization of topological wave functions, the vacancy density, and the electron-electron interaction strength with the topological phase robustness. We demonstrate that electron-electron interactions play a crucial role in degrading topological phases thereby determining the validity of single-particle approximations for topological insulator phases. Our findings can be naturally extended to virtual topological phases of a wide range of materials.
Freire, Rafael L. H.; Lima, F. Crasto; Miwa, Roberto H.; Fazzio, Adalberto
Exploring topological transport in Pt2HgSe3 nanoribbons: Insights for spintronic device integration Journal Article
Em: Phys. Rev. B, vol. 110, iss. 3, pp. 035111, 2024.
@article{PhysRevB.110.035111,
title = {Exploring topological transport in Pt2HgSe3 nanoribbons: Insights for spintronic device integration},
author = {Rafael L. H. Freire and F. Crasto Lima and Roberto H. Miwa and Adalberto Fazzio},
url = {https://link.aps.org/doi/10.1103/PhysRevB.110.035111},
doi = {10.1103/PhysRevB.110.035111},
year = {2024},
date = {2024-07-02},
urldate = {2024-07-01},
journal = {Phys. Rev. B},
volume = {110},
issue = {3},
pages = {035111},
publisher = {American Physical Society},
abstract = {The discovery of the quantum spin Hall effect led to the exploration of the electronic transport for spintronic devices. We theoretically investigated the electronic conductance in large-gap realistic quantum spin Hall system Pt2HgSe3 nanoribbons. By an ab initio approach, we found that the edge states present a penetration depth of about 0.9 nm, much smaller than those predicted in other two-dimensional topological systems, thus, suggesting that Pt2HgSe3 allows the exploitation of topological transport properties in narrow ribbons. Using nonequilibrium Green's function calculations, we have examined the electron conductivity upon the presence of Se↔Hg antistructure defects randomly distributed in the Pt2HgSe3 scattering region. By considering scattering lengths up to 109 nm, we found localization lengths that can surpass micrometer sizes for narrow nanoribbons (<9 nm). These findings can contribute to further understanding the behavior of topological insulators under realistic conditions and their integration within electronic spintronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The discovery of the quantum spin Hall effect led to the exploration of the electronic transport for spintronic devices. We theoretically investigated the electronic conductance in large-gap realistic quantum spin Hall system Pt2HgSe3 nanoribbons. By an ab initio approach, we found that the edge states present a penetration depth of about 0.9 nm, much smaller than those predicted in other two-dimensional topological systems, thus, suggesting that Pt2HgSe3 allows the exploitation of topological transport properties in narrow ribbons. Using nonequilibrium Green's function calculations, we have examined the electron conductivity upon the presence of Se↔Hg antistructure defects randomly distributed in the Pt2HgSe3 scattering region. By considering scattering lengths up to 109 nm, we found localization lengths that can surpass micrometer sizes for narrow nanoribbons (<9 nm). These findings can contribute to further understanding the behavior of topological insulators under realistic conditions and their integration within electronic spintronic devices.
Oliveira, I. S. S.; Lima, Erika Nascimento; Miwa, Roberto H.; Deus, Dominike P. Andrade
Unveiling the electronic properties of BiP3 triphosphide from bulk to graphene-based heterostructures by first-principles calculations Journal Article
Em: Applied Surface Science, pp. 160041, 2024, ISSN: 0169-4332.
@article{DEOLIVEIRA2024160041,
title = {Unveiling the electronic properties of BiP3 triphosphide from bulk to graphene-based heterostructures by first-principles calculations},
author = {I. S. S. Oliveira and Erika Nascimento Lima and Roberto H. Miwa and Dominike P. Andrade Deus},
url = {https://www.sciencedirect.com/science/article/pii/S0169433224007542},
doi = {https://doi.org/10.1016/j.apsusc.2024.160041},
issn = {0169-4332},
year = {2024},
date = {2024-04-10},
urldate = {2024-04-10},
journal = {Applied Surface Science},
pages = {160041},
abstract = {In our study, we conduct the structural and electronic properties of bismuth triphosphide (BiP3) in its bulk, few-layer, and monolayer forms. We found that BiP3 in bulk exhibits a metallic stable layered structure. The exfoliation energy of 1.07 J/m2 indicates ease exfoliation, comparable to other triphosphides. The band gap varies with thickness, transitioning from semiconductor—metal between four to five layers, influenced by interlayer coupling and quantum confinement. We also investigated the heterostructure created by depositing graphene (G) on few-layer BiP3. In monolayer (G/m-BiP3) and bilayer (G/2L-BiP3) forms, a metal–semiconductor junction is formed, characterized by weak vdW interactions at the interface and exhibiting p-type Schottky contacts. We observed that the Schottky Barrier Height (SBH) can be modulated by altering the interlayer distance between G and BiP3. This adjustment allows transitions between n-type and p-type Schottky contacts in G/m-BiP3 and the formation of an ohmic contact in G/2L-BiP3. Furthermore, applying an electric field affects the SBH, leading to similar transitions and the development of an ohmic contact. Additionally, our study shows that n-doping in graphene increases with the number of BiP3 layers and external electric field application. These properties position BiP3 few-layer as a promising material for nanoelectronic, optoelectronic, and graphene-based devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In our study, we conduct the structural and electronic properties of bismuth triphosphide (BiP3) in its bulk, few-layer, and monolayer forms. We found that BiP3 in bulk exhibits a metallic stable layered structure. The exfoliation energy of 1.07 J/m2 indicates ease exfoliation, comparable to other triphosphides. The band gap varies with thickness, transitioning from semiconductor—metal between four to five layers, influenced by interlayer coupling and quantum confinement. We also investigated the heterostructure created by depositing graphene (G) on few-layer BiP3. In monolayer (G/m-BiP3) and bilayer (G/2L-BiP3) forms, a metal–semiconductor junction is formed, characterized by weak vdW interactions at the interface and exhibiting p-type Schottky contacts. We observed that the Schottky Barrier Height (SBH) can be modulated by altering the interlayer distance between G and BiP3. This adjustment allows transitions between n-type and p-type Schottky contacts in G/m-BiP3 and the formation of an ohmic contact in G/2L-BiP3. Furthermore, applying an electric field affects the SBH, leading to similar transitions and the development of an ohmic contact. Additionally, our study shows that n-doping in graphene increases with the number of BiP3 layers and external electric field application. These properties position BiP3 few-layer as a promising material for nanoelectronic, optoelectronic, and graphene-based devices.
Kuritza, Danilo; Miwa, Roberto H.; Padilha, José E.
Directional dependence of the electronic and transport properties of Biphenylene under strain conditions Journal Article
Em: Phys. Chem. Chem. Phys., pp. -, 2024.
@article{D4CP00033A,
title = {Directional dependence of the electronic and transport properties of Biphenylene under strain conditions},
author = {Danilo Kuritza and Roberto H. Miwa and José E. Padilha},
url = {http://dx.doi.org/10.1039/D4CP00033A},
doi = {10.1039/D4CP00033A},
year = {2024},
date = {2024-03-26},
urldate = {2024-01-01},
journal = {Phys. Chem. Chem. Phys.},
pages = {-},
publisher = {The Royal Society of Chemistry},
abstract = {In this study, we investigated the electronic and electronic transport properties of biphenylene (BPN) using first-principles density functional theory (DFT) calculations combined with the non-equilibrium Green's function (NEGF) formalism. We have focused on understanding the electronic properties of BPN, and the anisotropic behavior of electronic transport upon external strain. We found the emergence of electronic stripes (ESs) on the BPN surface and the formation of type-II Dirac cone near the Fermi level. In the sequence, the electronic transport results reveal that such ESs dictate the anisotropic behavior of the transmission function. Finally, we show that the tuning of the (anisotropic) electronic current, mediated by external mechanical strain, is ruled by the energy position of the lowest unoccupied states with wave-vectors perpedicular to the ESs. This control could be advantageous for applications in nanoelectronic devices that require precise control of current direction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, we investigated the electronic and electronic transport properties of biphenylene (BPN) using first-principles density functional theory (DFT) calculations combined with the non-equilibrium Green's function (NEGF) formalism. We have focused on understanding the electronic properties of BPN, and the anisotropic behavior of electronic transport upon external strain. We found the emergence of electronic stripes (ESs) on the BPN surface and the formation of type-II Dirac cone near the Fermi level. In the sequence, the electronic transport results reveal that such ESs dictate the anisotropic behavior of the transmission function. Finally, we show that the tuning of the (anisotropic) electronic current, mediated by external mechanical strain, is ruled by the energy position of the lowest unoccupied states with wave-vectors perpedicular to the ESs. This control could be advantageous for applications in nanoelectronic devices that require precise control of current direction.
Orellana, Walter; Miwa, Roberto H.
Fe and Co adatoms on bilayer borophene as single-atom catalysts for the oxygen-reduction reaction: A theoretical study Journal Article
Em: Phys. Rev. Appl., vol. 21, iss. 3, pp. 034008, 2024.
@article{PhysRevApplied.21.034008,
title = {Fe and Co adatoms on bilayer borophene as single-atom catalysts for the oxygen-reduction reaction: A theoretical study},
author = {Walter Orellana and Roberto H. Miwa},
url = {https://link.aps.org/doi/10.1103/PhysRevApplied.21.034008},
doi = {10.1103/PhysRevApplied.21.034008},
year = {2024},
date = {2024-03-01},
urldate = {2024-03-01},
journal = {Phys. Rev. Appl.},
volume = {21},
issue = {3},
pages = {034008},
publisher = {American Physical Society},
abstract = {This study employs first-principles density-functional-theory (DFT) calculations and ab initio molecular dynamic (AIMD) simulations to investigate the stability, electronic properties, and oxygen-reduction reaction (ORR) activity of M adatoms ( M = Fe , Co ) on free-standing bilayer borophene (BB) with different coverages. Our findings indicate that metals strongly bind to the BB surface, particularly at the hollow sites, inducing metallicity. We analyze the dissociation energy of O 2 and OOH after the adsorption on the metal center of BBM while ORR activity was assessed through the free-energy adsorption of their intermediates. The stability of the systems at electrochemical conditions was investigated by Pourbaix analysis as well as by AIMD simulations, which include explicit solvents. Our results suggest that BBCo in a low-coverage adatom configuration would exhibit competitive ORR activity, with a theoretical overpotential of around 1 V. However, this activity would only be feasible in alkaline environments where the stability BBCo is preserved. Hubbard- U corrections and the hybrid functional approaches within DFT are taken into consideration, and subsequent results are compared.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study employs first-principles density-functional-theory (DFT) calculations and ab initio molecular dynamic (AIMD) simulations to investigate the stability, electronic properties, and oxygen-reduction reaction (ORR) activity of M adatoms ( M = Fe , Co ) on free-standing bilayer borophene (BB) with different coverages. Our findings indicate that metals strongly bind to the BB surface, particularly at the hollow sites, inducing metallicity. We analyze the dissociation energy of O 2 and OOH after the adsorption on the metal center of BBM while ORR activity was assessed through the free-energy adsorption of their intermediates. The stability of the systems at electrochemical conditions was investigated by Pourbaix analysis as well as by AIMD simulations, which include explicit solvents. Our results suggest that BBCo in a low-coverage adatom configuration would exhibit competitive ORR activity, with a theoretical overpotential of around 1 V. However, this activity would only be feasible in alkaline environments where the stability BBCo is preserved. Hubbard- U corrections and the hybrid functional approaches within DFT are taken into consideration, and subsequent results are compared.
Freire, Rafael L. H.; Lima, F. Crasto; Miwa, Roberto H.; Fazzio, Adalberto
Exploring Topological Transport in Pt$_2$HgSe$_3$ Nanoribbons: Insights for Spintronic Device Integration Working paper
2024.
@workingpaper{freire2024exploring,
title = {Exploring Topological Transport in Pt$_2$HgSe$_3$ Nanoribbons: Insights for Spintronic Device Integration},
author = {Rafael L. H. Freire and F. Crasto Lima and Roberto H. Miwa and Adalberto Fazzio},
url = {https://arxiv.org/abs/2405.06861v1},
doi = {https://doi.org/10.48550/arXiv.2405.06861},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
abstract = {The discovery of the quantum spin Hall effect led to the exploration of the electronic transport for spintronic devices. Here, we theoretically investigated the electronic conductance in large-gap realistic quantum spin Hall system, Pt2HgSe3 nanoribbons. By an ab initio approach, we found that the edge states present a penetration depth of about 0.9,nm, which is much smaller than those predicted in other 2D topological systems. Thus, suggesting that Pt2HgSe3 allows the exploitation of topological transport properties in narrow ribbons. Using non-equilibrium Green's functions calculations, we have examined the electron conductivity upon the presence of Se,↔,Hg antistructure defects randomly distributed in the Pt2HgSe3 scattering region. By considering scattering lengths up to 109,nm, we found localization lengths that can surpass μm sizes for narrow nanoribbons (<9,nm). These findings can contribute to further understanding the behavior of topological insulators under realistic conditions and their integration within electronic, spintronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
The discovery of the quantum spin Hall effect led to the exploration of the electronic transport for spintronic devices. Here, we theoretically investigated the electronic conductance in large-gap realistic quantum spin Hall system, Pt2HgSe3 nanoribbons. By an ab initio approach, we found that the edge states present a penetration depth of about 0.9,nm, which is much smaller than those predicted in other 2D topological systems. Thus, suggesting that Pt2HgSe3 allows the exploitation of topological transport properties in narrow ribbons. Using non-equilibrium Green's functions calculations, we have examined the electron conductivity upon the presence of Se,↔,Hg antistructure defects randomly distributed in the Pt2HgSe3 scattering region. By considering scattering lengths up to 109,nm, we found localization lengths that can surpass μm sizes for narrow nanoribbons (<9,nm). These findings can contribute to further understanding the behavior of topological insulators under realistic conditions and their integration within electronic, spintronic devices.
2023
Souza, P. H.; Padilha, José E.; Miwa, Roberto H.
Spin-polarized nearly-free electron channels on the Ca$_2$N electrenes Working paper
2023.
@workingpaper{souza2023spinpolarized,
title = {Spin-polarized nearly-free electron channels on the Ca$_2$N electrenes},
author = {P. H. Souza and José E. Padilha and Roberto H. Miwa},
url = {https://arxiv.org/abs/2312.06447},
doi = {https://doi.org/10.48550/arXiv.2312.06447},
year = {2023},
date = {2023-12-12},
urldate = {2023-12-12},
abstract = {Two-dimensional (2D) materials combined with the presence of surface nearly-free electrons (NFE) have been considered quite interesting platforms to be exploited for the development of 2D electronic devices. Further incorporation of foreign elements adds a new degree of freedom to engineer the electronic as well as the magnetic properties of 2D materials. Here we have performed an ab-initio study of Ca2N, electrenes fully (i.e., both sides) adsorbed by hydrogen (H/Ca2N/H) and fluorine (F/Ca2N/F) atoms. The NFE states are suppressed in these systems, followed by the appearance of a net magnetic moment localized in the nitrogen atoms intercalated by the hydrogenated or fluorinated calcium layers. In the sequence, we have proposed lateral heterostructures combining the H/Ca2N/H or F/Ca2N/F regions with pristine Ca2N, electrenes [(Ca2N)(X/Ca2N/X), with X=H or F]. We found that the magnetic moment of the hydrogenated or fluorinated regions promotes the emergence of spin-polarized NFE states confined along the pristine (Ca2N) stripes. Further electronic transport calculations reveal that the (X/Ca2N/X) regions act as spin-dependent scattering centers, spin-filters. We believe that these findings make an important contribution to the development of spintronic devices based on 2D electrides.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
Two-dimensional (2D) materials combined with the presence of surface nearly-free electrons (NFE) have been considered quite interesting platforms to be exploited for the development of 2D electronic devices. Further incorporation of foreign elements adds a new degree of freedom to engineer the electronic as well as the magnetic properties of 2D materials. Here we have performed an ab-initio study of Ca2N, electrenes fully (i.e., both sides) adsorbed by hydrogen (H/Ca2N/H) and fluorine (F/Ca2N/F) atoms. The NFE states are suppressed in these systems, followed by the appearance of a net magnetic moment localized in the nitrogen atoms intercalated by the hydrogenated or fluorinated calcium layers. In the sequence, we have proposed lateral heterostructures combining the H/Ca2N/H or F/Ca2N/F regions with pristine Ca2N, electrenes [(Ca2N)(X/Ca2N/X), with X=H or F]. We found that the magnetic moment of the hydrogenated or fluorinated regions promotes the emergence of spin-polarized NFE states confined along the pristine (Ca2N) stripes. Further electronic transport calculations reveal that the (X/Ca2N/X) regions act as spin-dependent scattering centers, spin-filters. We believe that these findings make an important contribution to the development of spintronic devices based on 2D electrides.
Perin, Gabriel; Kuritza, Danilo; Barbosa, Rafael; Tresco, Gustavo; Pontes, Renato B.; Miwa, Roberto H.; Padilha, José E.
Em: Phys. Rev. Mater., vol. 7, iss. 10, pp. 104003, 2023.
@article{PhysRevMaterials.7.104003,
title = {First-principles study of bilayers $mathrmZnX$ and $mathrmCdX$ ($X=mathrmS,mathrmSe,mathrmTe$) direct band-gap semiconductors and their van der Waals heterostructures},
author = {Gabriel Perin and Danilo Kuritza and Rafael Barbosa and Gustavo Tresco and Renato B. Pontes and Roberto H. Miwa and José E. Padilha},
url = {https://link.aps.org/doi/10.1103/PhysRevMaterials.7.104003},
doi = {10.1103/PhysRevMaterials.7.104003},
year = {2023},
date = {2023-10-01},
urldate = {2023-10-01},
journal = {Phys. Rev. Mater.},
volume = {7},
issue = {10},
pages = {104003},
publisher = {American Physical Society},
abstract = {We conducted comprehensive first-principles investigations of the structural, electronic, and optical properties of hexagonal
Zn
X
and
Cd
X
(
X =
S
,
Se
,
Te
) and their van der Waals heterostructures. Our results indicate that all materials are thermally and dynamically stable, in contrast to earlier works. Electronic structure calculations with a hybrid functional revealed that the bilayers
Zn
X
and
Cd
X
are characterized by a direct band gap (at the
Γ
point), primarily lies within the visible spectrum of the sunlight (with an exception for ZnS). Moreover, we found the band edges (VBM/CBM of the bilayers) lying below/above the oxidation/reduction potentials (
E
O
2
/
H
2
O
/
E
H
+
/
H
2
) depending on the environment's pH. The effects of mechanical strain on the electronic properties of the bilayers have been thoroughly investigated, revealing an impressive tunability of the band gap, energy position of the band edges, and the ratio of the electron and hole effective masses. The calculated optical absorption spectra showed that the bilayers
Zn
X
and
Cd
X
, with the exception of ZnS, absorb in the visible region. Besides that, we found exciton binding energies between 0.30 and 0.96 eV for ZnTe and CdS bilayers, confirming that the reduced screening effect in 2D systems leads to higher values of exciton binding energies. Furthermore, our results indicated that the ZnTe/CdS heterostructure exhibits a band gap within the visible sunlight spectra. The band edges are located in the bilayer ZnTe resulting in a type-I band offset. However, upon compressive strain, we verified the emergence of the type-II band alignment, as a result, the first absorption peak is redshifted and the exciton exciton wave function spreads out in both materials. Overall, our findings provide valuable insights into the potential of these materials for various technological applications in the fields of the photonics, photocatalysis, and optoelectronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We conducted comprehensive first-principles investigations of the structural, electronic, and optical properties of hexagonal
Zn
X
and
Cd
X
(
X =
S
,
Se
,
Te
) and their van der Waals heterostructures. Our results indicate that all materials are thermally and dynamically stable, in contrast to earlier works. Electronic structure calculations with a hybrid functional revealed that the bilayers
Zn
X
and
Cd
X
are characterized by a direct band gap (at the
Γ
point), primarily lies within the visible spectrum of the sunlight (with an exception for ZnS). Moreover, we found the band edges (VBM/CBM of the bilayers) lying below/above the oxidation/reduction potentials (
E
O
2
/
H
2
O
/
E
H
+
/
H
2
) depending on the environment's pH. The effects of mechanical strain on the electronic properties of the bilayers have been thoroughly investigated, revealing an impressive tunability of the band gap, energy position of the band edges, and the ratio of the electron and hole effective masses. The calculated optical absorption spectra showed that the bilayers
Zn
X
and
Cd
X
, with the exception of ZnS, absorb in the visible region. Besides that, we found exciton binding energies between 0.30 and 0.96 eV for ZnTe and CdS bilayers, confirming that the reduced screening effect in 2D systems leads to higher values of exciton binding energies. Furthermore, our results indicated that the ZnTe/CdS heterostructure exhibits a band gap within the visible sunlight spectra. The band edges are located in the bilayer ZnTe resulting in a type-I band offset. However, upon compressive strain, we verified the emergence of the type-II band alignment, as a result, the first absorption peak is redshifted and the exciton exciton wave function spreads out in both materials. Overall, our findings provide valuable insights into the potential of these materials for various technological applications in the fields of the photonics, photocatalysis, and optoelectronics.
Zn
X
and
Cd
X
(
X =
S
,
Se
,
Te
) and their van der Waals heterostructures. Our results indicate that all materials are thermally and dynamically stable, in contrast to earlier works. Electronic structure calculations with a hybrid functional revealed that the bilayers
Zn
X
and
Cd
X
are characterized by a direct band gap (at the
Γ
point), primarily lies within the visible spectrum of the sunlight (with an exception for ZnS). Moreover, we found the band edges (VBM/CBM of the bilayers) lying below/above the oxidation/reduction potentials (
E
O
2
/
H
2
O
/
E
H
+
/
H
2
) depending on the environment's pH. The effects of mechanical strain on the electronic properties of the bilayers have been thoroughly investigated, revealing an impressive tunability of the band gap, energy position of the band edges, and the ratio of the electron and hole effective masses. The calculated optical absorption spectra showed that the bilayers
Zn
X
and
Cd
X
, with the exception of ZnS, absorb in the visible region. Besides that, we found exciton binding energies between 0.30 and 0.96 eV for ZnTe and CdS bilayers, confirming that the reduced screening effect in 2D systems leads to higher values of exciton binding energies. Furthermore, our results indicated that the ZnTe/CdS heterostructure exhibits a band gap within the visible sunlight spectra. The band edges are located in the bilayer ZnTe resulting in a type-I band offset. However, upon compressive strain, we verified the emergence of the type-II band alignment, as a result, the first absorption peak is redshifted and the exciton exciton wave function spreads out in both materials. Overall, our findings provide valuable insights into the potential of these materials for various technological applications in the fields of the photonics, photocatalysis, and optoelectronics.
Deus, Dominike P. Andrade; Oliveira, Igor S. S.; Miwa, Roberto H.; Lima, Erika Nascimento
Unveiling the electronic properties of BiP$_3$ triphosphide from bulk to graphene-based heterostructure by first-principles calculations Journal Article
Em: 2023.
@article{deus2023unveilingb,
title = {Unveiling the electronic properties of BiP$_3$ triphosphide from bulk to graphene-based heterostructure by first-principles calculations},
author = {Dominike P. Andrade Deus and Igor S. S. Oliveira and Roberto H. Miwa and Erika Nascimento Lima},
url = {https://ui.adsabs.harvard.edu/abs/2023arXiv230902216D/abstract},
doi = {https://doi.org/10.48550/arXiv.2309.02216},
year = {2023},
date = {2023-09-08},
urldate = {2023-01-01},
abstract = {Triphosphides, with a chemical formula of XP3 (X is a group IIIA, IVA, or VA element), have recently attracted much attention due to their great potential in several applications. Here, using density functional theory calculations, we describe for the first time the structural and electronic properties of the bulk bismuth triphosphide (BiP3). Phonon spectra and molecular dynamics simulations confirm that the 3D crystal of BiP3 is a metal thermodynamically stable with no bandgap. Unlike the bulk, the mono-, bi-, tri-, and tetra-layers of BiP3 are semiconductors with a bandgap ranging from 1.4 to 0.06 eV. However, stackings with more than five layers exhibit metallic behavior equal to the bulk. The results show that quantum confinement is a powerful tool for tuning the electronic properties of BiP3 triphosphide, making it suitable for technological applications. Building on this, the electronic properties of van der Waals heterostructure constructed by graphene (G) and the BiP3 monolayer (m-BiP3) were investigated. Our results show that the Dirac cone in graphene remains intact in this heterostructure. At the equilibrium interlayer distance, the G/m-BiP3 forms an n-type contact with a Schottky barrier height of 0.5 eV. It is worth noting that the SHB in the G/m-BiP3 heterostructure can be adjusted by changing the interlayer distance or applying a transverse electric field. Thus, we show that few-layers BiP3 is an interesting material for realizing nanoelectronic and optoelectronic devices and is an excellent option for designing Schottky nanoelectronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Triphosphides, with a chemical formula of XP3 (X is a group IIIA, IVA, or VA element), have recently attracted much attention due to their great potential in several applications. Here, using density functional theory calculations, we describe for the first time the structural and electronic properties of the bulk bismuth triphosphide (BiP3). Phonon spectra and molecular dynamics simulations confirm that the 3D crystal of BiP3 is a metal thermodynamically stable with no bandgap. Unlike the bulk, the mono-, bi-, tri-, and tetra-layers of BiP3 are semiconductors with a bandgap ranging from 1.4 to 0.06 eV. However, stackings with more than five layers exhibit metallic behavior equal to the bulk. The results show that quantum confinement is a powerful tool for tuning the electronic properties of BiP3 triphosphide, making it suitable for technological applications. Building on this, the electronic properties of van der Waals heterostructure constructed by graphene (G) and the BiP3 monolayer (m-BiP3) were investigated. Our results show that the Dirac cone in graphene remains intact in this heterostructure. At the equilibrium interlayer distance, the G/m-BiP3 forms an n-type contact with a Schottky barrier height of 0.5 eV. It is worth noting that the SHB in the G/m-BiP3 heterostructure can be adjusted by changing the interlayer distance or applying a transverse electric field. Thus, we show that few-layers BiP3 is an interesting material for realizing nanoelectronic and optoelectronic devices and is an excellent option for designing Schottky nanoelectronic devices.
Deus, Dominike P. Andrade; Lopes, João Marcelo J.; Miwa, Roberto H.
Em: Carbon, vol. 213, 2023, ISSN: 0008-6223.
@article{Deus2023,
title = {Stacking order effects on the energetics and electronic properties of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg" display="inline" id="d1e860"><mml:mi>n</mml:mi></mml:math>-doped graphene/h-BN van der Waals heterostructures on SiC(0001)},
author = {Dominike P. Andrade Deus and João Marcelo J. Lopes and Roberto H. Miwa},
doi = {10.1016/j.carbon.2023.118244},
issn = {0008-6223},
year = {2023},
date = {2023-09-01},
journal = {Carbon},
volume = {213},
publisher = {Elsevier BV},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Aslla-Quispe, A. P.; Cruz-Yupanqui, G. M.; Miwa, Roberto H.; Guerra, J. D. S.
Ab initio study of samarium doped barium titanate Journal Article
Em: Ferroelectrics, vol. 611, não 1, pp. 13–24, 2023, ISSN: 1563-5112.
@article{Aslla-Quispe2023,
title = {Ab initio study of samarium doped barium titanate},
author = {A. P. Aslla-Quispe and G. M. Cruz-Yupanqui and Roberto H. Miwa and J. D. S. Guerra},
doi = {10.1080/00150193.2023.2201765},
issn = {1563-5112},
year = {2023},
date = {2023-07-27},
urldate = {2023-07-27},
journal = {Ferroelectrics},
volume = {611},
number = {1},
pages = {13–24},
publisher = {Informa UK Limited},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Lima, F. Crasto; Focassio, B; Miwa, Roberto H.; Fazzio, Adalberto
Topological insulating phase arising in transition metal dichalcogenide alloy Journal Article
Em: 2D Materials, vol. 10, não 3, pp. 035001, 2023.
@article{CrastodeLima_2023,
title = {Topological insulating phase arising in transition metal dichalcogenide alloy},
author = {F. Crasto Lima and B Focassio and Roberto H. Miwa and Adalberto Fazzio},
url = {https://dx.doi.org/10.1088/2053-1583/acc670},
doi = {10.1088/2053-1583/acc670},
year = {2023},
date = {2023-04-01},
urldate = {2023-04-01},
journal = {2D Materials},
volume = {10},
number = {3},
pages = {035001},
publisher = {IOP Publishing},
abstract = {Transition metal dichalcogenides have been the subject of numerous studies addressing technological applications and fundamental issues. Single-layer PtSe2 is a semiconductor with a trivial bandgap, in contrast, its counterpart with of Se atoms substituted by Hg, Pt2HgSe3 (jacutingaite, a naturally occurring mineral) is a 2D topological insulator with a large bandgap. Based on ab-initio calculations, we investigate the energetic stability, and the topological transition in Pt(Hg x Se)2 as a function of alloy concentration, and the distribution of Hg atoms embedded in the PtSe2 host. Our findings reveal the dependence of the topological phase with respect to the alloy concentration and robustness with respect to the distribution of Hg. Through a combination of our ab-initio results and a defect wave function percolation model, we estimate the random alloy concentration threshold for the topological transition to be only . Our results expand the possible search for non-trivial topological phases in random alloy systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Transition metal dichalcogenides have been the subject of numerous studies addressing technological applications and fundamental issues. Single-layer PtSe2 is a semiconductor with a trivial bandgap, in contrast, its counterpart with of Se atoms substituted by Hg, Pt2HgSe3 (jacutingaite, a naturally occurring mineral) is a 2D topological insulator with a large bandgap. Based on ab-initio calculations, we investigate the energetic stability, and the topological transition in Pt(Hg x Se)2 as a function of alloy concentration, and the distribution of Hg atoms embedded in the PtSe2 host. Our findings reveal the dependence of the topological phase with respect to the alloy concentration and robustness with respect to the distribution of Hg. Through a combination of our ab-initio results and a defect wave function percolation model, we estimate the random alloy concentration threshold for the topological transition to be only . Our results expand the possible search for non-trivial topological phases in random alloy systems.
Silvestre, G. H.; Lima, F. Crasto; Bernardes, J. S.; Fazzio, Adalberto; Miwa, Roberto H.
Nanoscale structural and electronic properties of cellulose/graphene interfaces Journal Article
Em: Phys. Chem. Chem. Phys., vol. 25, não 2, pp. 1161–1168, 2023, ISSN: 1463-9084.
@article{Silvestre2023,
title = {Nanoscale structural and electronic properties of cellulose/graphene interfaces},
author = {G. H. Silvestre and F. Crasto Lima and J. S. Bernardes and Adalberto Fazzio and Roberto H. Miwa},
doi = {10.1039/d2cp04146d},
issn = {1463-9084},
year = {2023},
date = {2023-01-04},
urldate = {2023-01-04},
journal = {Phys. Chem. Chem. Phys.},
volume = {25},
number = {2},
pages = {1161–1168},
publisher = {Royal Society of Chemistry (RSC)},
abstract = {<jats:p>The development of electronic devices based on the functionalization of (nano)cellulose platforms relies upon an atomistic understanding of the structural and electronic properties of a combined system, cellulose/functional element.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>The development of electronic devices based on the functionalization of (nano)cellulose platforms relies upon an atomistic understanding of the structural and electronic properties of a combined system, cellulose/functional element.</jats:p>
Scopel, Wanderlã L.; Lima, F. Crasto; Souza, Pedro H.; Padilha, José E.; Miwa, Roberto H.
Bridging Borophene and Metal Surfaces: Structural, Electronic, and Electron Transport Properties Journal Article
Em: The Journal of Physical Chemistry C, vol. 127, não 35, pp. 17556-17566, 2023.
@article{doi:10.1021/acs.jpcc.3c03123,
title = {Bridging Borophene and Metal Surfaces: Structural, Electronic, and Electron Transport Properties},
author = {Wanderlã L. Scopel and F. Crasto Lima and Pedro H. Souza and José E. Padilha and Roberto H. Miwa},
url = {https://doi.org/10.1021/acs.jpcc.3c03123},
doi = {10.1021/acs.jpcc.3c03123},
year = {2023},
date = {2023-01-01},
journal = {The Journal of Physical Chemistry C},
volume = {127},
number = {35},
pages = {17556-17566},
abstract = {Currently, solid interfaces composed of two-dimensional materials (2D) in contact with metal surfaces (m-surf) have been the subject of intense research, where the borophene bilayer (BBL) has been considered a prominent material for the development of electronic devices based on 2D platforms. In this work, we present a theoretical study of the energetic, structural, and electronic properties of the BBL/m-surf interface, with m-surf = Ag(111), Au(111), and Al(111) surfaces, and the electronic transport properties of BBL channels connected to the BBL/m-surf top contacts. We find that the BBL becomes metallized due to hybridization with the metal surface states, resulting in Ohmic contacts between BBL and m-surf. However, the projected wavefunctions indicate that the inner and top-most boron layers have a weaker interaction with the m-surf, thus retaining their semiconducting character. The net charge transfers reveal that BBL has become n-type (p-type) doped for m-surf = Ag and Al (= Au). A thorough structural characterization of the BBL/m-surf interface, using a series of simulations of X-ray photoelectron spectra, shows that the formation of the BBL/m-surf interface is characterized by a red shift of the B-1s spectra. Further electronic transport results revealed the emergence of a Schottky barrier between 0.1 and 0.2 eV between the BBL/m-surf contact and the BBL channels. We believe that our findings are timely, bringing important contributions to the applicability of BBLs for developing 2D electronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Currently, solid interfaces composed of two-dimensional materials (2D) in contact with metal surfaces (m-surf) have been the subject of intense research, where the borophene bilayer (BBL) has been considered a prominent material for the development of electronic devices based on 2D platforms. In this work, we present a theoretical study of the energetic, structural, and electronic properties of the BBL/m-surf interface, with m-surf = Ag(111), Au(111), and Al(111) surfaces, and the electronic transport properties of BBL channels connected to the BBL/m-surf top contacts. We find that the BBL becomes metallized due to hybridization with the metal surface states, resulting in Ohmic contacts between BBL and m-surf. However, the projected wavefunctions indicate that the inner and top-most boron layers have a weaker interaction with the m-surf, thus retaining their semiconducting character. The net charge transfers reveal that BBL has become n-type (p-type) doped for m-surf = Ag and Al (= Au). A thorough structural characterization of the BBL/m-surf interface, using a series of simulations of X-ray photoelectron spectra, shows that the formation of the BBL/m-surf interface is characterized by a red shift of the B-1s spectra. Further electronic transport results revealed the emergence of a Schottky barrier between 0.1 and 0.2 eV between the BBL/m-surf contact and the BBL channels. We believe that our findings are timely, bringing important contributions to the applicability of BBLs for developing 2D electronic devices.
Barbosa, Rafael; Kuritza, Danilo; Perin, Gabriel; Miwa, Roberto H.; Pontes, R. B.; Padilha, José E.
Electronic and optical properties of Janus-like hexagonal monolayer materials of group IV-VI Journal Article
Em: Phys. Rev. Mater., vol. 7, iss. 1, pp. 014001, 2023.
@article{PhysRevMaterials.7.014001,
title = {Electronic and optical properties of Janus-like hexagonal monolayer materials of group IV-VI},
author = {Rafael Barbosa and Danilo Kuritza and Gabriel Perin and Roberto H. Miwa and R. B. Pontes and José E. Padilha},
url = {https://link.aps.org/doi/10.1103/PhysRevMaterials.7.014001},
doi = {10.1103/PhysRevMaterials.7.014001},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Phys. Rev. Mater.},
volume = {7},
issue = {1},
pages = {014001},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Lopes, Emmanuel V. C.; Baierle, Rogerio J.; Miwa, Roberto H.; Schmidt, Tome M.
Noncentrosymmetric two-dimensional Weyl semimetals in porous Si/Ge structures Working paper
2023.
@workingpaper{lopes2023noncentrosymmetric,
title = {Noncentrosymmetric two-dimensional Weyl semimetals in porous Si/Ge structures},
author = {Emmanuel V. C. Lopes and Rogerio J. Baierle and Roberto H. Miwa and Tome M. Schmidt},
url = {https://arxiv.org/abs/2305.05756},
doi = {10.48550/arXiv.2305.05756},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
abstract = {In this work we predict a family of noncentrosymmetric two-dimensional (2D) Weyl semimetals composed by porous Ge and SiGe structures. These systems are energetically stable graphenylene-like structures with a buckling, spontaneously breaking the inversion symmetry. The nontrivial topological phase for these 2D systems occurs just below the Fermi level, resulting in nonvanishing Berry curvature around the Weyl nodes. The emerged Weyl semimetals are protected by C3 symmetry, presenting one-dimensional edge Fermi-arcs connecting Weyl points with opposite chiralities. Our findings complete the family of Weyl in condensed-matter physics, by predicting the first noncentrosymmetric class of 2D Weyl semimetals.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
In this work we predict a family of noncentrosymmetric two-dimensional (2D) Weyl semimetals composed by porous Ge and SiGe structures. These systems are energetically stable graphenylene-like structures with a buckling, spontaneously breaking the inversion symmetry. The nontrivial topological phase for these 2D systems occurs just below the Fermi level, resulting in nonvanishing Berry curvature around the Weyl nodes. The emerged Weyl semimetals are protected by C3 symmetry, presenting one-dimensional edge Fermi-arcs connecting Weyl points with opposite chiralities. Our findings complete the family of Weyl in condensed-matter physics, by predicting the first noncentrosymmetric class of 2D Weyl semimetals.
Deus, Dominike P. Andrade; Oliveira, Igor S. S.; Miwa, Roberto H.; Nascimento, Erika L.
Unveiling the electronic properties of BiP3 triphosphide from bulk to heterostructures by first principles calculations Working paper
2023.
@workingpaper{deus2023unveiling,
title = {Unveiling the electronic properties of BiP3 triphosphide from bulk to heterostructures by first principles calculations},
author = {Dominike P. Andrade Deus and Igor S. S. Oliveira and Roberto H. Miwa and Erika L. Nascimento},
url = {https://arxiv.org/abs/2309.02216},
doi = {10.48550/arXiv.2309.02216},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
abstract = {Triphosphides, with a chemical formula of XP3 (X is a group IIIA, IVA, or VA element), have recently attracted much attention due to their great potential in several applications. Here, using density functional theory calculations, we describe for the first time the structural and electronic properties of the bulk bismuth triphosphide (BiP3). Phonon spectra and molecular dynamics simulations confirm that the 3D crystal of BiP3 is a metal thermodynamically stable with no bandgap. Unlike the bulk, the mono-, bi-, tri-, and tetra-layers of BiP3 are semiconductors with a bandgap ranging from 1.4 to 0.06 eV. However, stackings with more than five layers exhibit metallic behavior equal to the bulk. The results show that quantum confinement is a powerful tool for tuning the electronic properties of BiP3 triphosphide, making it suitable for technological applications. Building on this, the electronic properties of van der Waals heterostructure constructed by graphene (G) and the bip~monolayer (m-bip) were investigated. Our results show that the Dirac cone in graphene remains intact in this heterostructure. At the equilibrium interlayer distance, the G/m-BiP3 forms an n-type contact with a Schottky barrier height of 0.5 eV. It is worth noting that the SHB in the G/m-BiP3 heterostructure can be adjusted by changing the interlayer distance or applying a transverse electric field. Thus, we show that few-layers bip~is an interesting material for realizing nanoelectronic and optoelectronic devices and is an excellent option for designing Schottky nanoelectronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
Triphosphides, with a chemical formula of XP3 (X is a group IIIA, IVA, or VA element), have recently attracted much attention due to their great potential in several applications. Here, using density functional theory calculations, we describe for the first time the structural and electronic properties of the bulk bismuth triphosphide (BiP3). Phonon spectra and molecular dynamics simulations confirm that the 3D crystal of BiP3 is a metal thermodynamically stable with no bandgap. Unlike the bulk, the mono-, bi-, tri-, and tetra-layers of BiP3 are semiconductors with a bandgap ranging from 1.4 to 0.06 eV. However, stackings with more than five layers exhibit metallic behavior equal to the bulk. The results show that quantum confinement is a powerful tool for tuning the electronic properties of BiP3 triphosphide, making it suitable for technological applications. Building on this, the electronic properties of van der Waals heterostructure constructed by graphene (G) and the bip~monolayer (m-bip) were investigated. Our results show that the Dirac cone in graphene remains intact in this heterostructure. At the equilibrium interlayer distance, the G/m-BiP3 forms an n-type contact with a Schottky barrier height of 0.5 eV. It is worth noting that the SHB in the G/m-BiP3 heterostructure can be adjusted by changing the interlayer distance or applying a transverse electric field. Thus, we show that few-layers bip~is an interesting material for realizing nanoelectronic and optoelectronic devices and is an excellent option for designing Schottky nanoelectronic devices.