We study theoretically the optical response for perfect zigzag-edge silicene nanoribbons with N silicon atoms of the A and B sublattices（N-ZSiNRs） under the irradiation of an external electromagnetic field at low te...We study theoretically the optical response for perfect zigzag-edge silicene nanoribbons with N silicon atoms of the A and B sublattices（N-ZSiNRs） under the irradiation of an external electromagnetic field at low temperatures.The 8- and 16-ZSiNRs are demonstrated to exhibit a broad energy regime of absorption coefficient, refractive index, extinction coefficient, and reflectivity from infrared to ultraviolet, utilizing the dipole-transition theorem for semiconductors. The optical spectra for 8- and 16-ZSiNRs may be classified into two types of the transitions,one between valence and conduction subbands with the same parity, and the other among the edge state and bulk state subbands. With the increase of the ribbon width, the optical spectra for ZSiNRs are proved to exhibit red shift and blue shift at the lower and higher energy regimes, respectively. The obtained novel features are believed to be of significance in designs of silicene-based optoelectronic devices.展开更多
The successfully experimental fabrication of two-dimensional Te monolayer films[Phys.Rev.Lett.119106101(2017)]has promoted the researches on the group-VI monolayer materials.In this work,the electronic structures and ...The successfully experimental fabrication of two-dimensional Te monolayer films[Phys.Rev.Lett.119106101(2017)]has promoted the researches on the group-VI monolayer materials.In this work,the electronic structures and topological properties of a group-VI binary compound of TeSe_(2) monolayers are studied based on the density functional theory and Wannier function method.Three types of structures,namely,a-TeSe_(2),b-TeSe_(2),and g-TeSe_(2),are proposed for the TeSe_(2) monolayer among which the a-TeSe_(2) is found being the most stable.All the three structures are semiconductors with indirect band gaps.Very interestingly,the g-TeSe_(2) monolayer becomes a quantum spin Hall(QSH)insulator with a global nontrivial energy gap of 0.14 eV when a 3.5%compressive strain is applied.The opening of the global band gap is understood by the competition between the decrease of the local band dispersion and the weakening of the interactions between the Se px,py orbitals and Te px,py orbitals during the process.Our work realizes topological states in the group-VI monolayers and promotes the potential applications of the materials in spintronics and quantum computations.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11664010 and 11264013the Hunan Provincial Natural Science Foundation of China under Grant Nos 2017JJ2217 and 12JJ4003+3 种基金the Scientific Research Fund of Hunan Provincial Education Department of China under Grant No 14B148the Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Provincethe Innovation Project for Postgraduate of Hunan Province under Grant No CX2015B549the Research Program of Jishou University under Grant Nos 15JDY026 and Jdy16021
文摘We study theoretically the optical response for perfect zigzag-edge silicene nanoribbons with N silicon atoms of the A and B sublattices（N-ZSiNRs） under the irradiation of an external electromagnetic field at low temperatures.The 8- and 16-ZSiNRs are demonstrated to exhibit a broad energy regime of absorption coefficient, refractive index, extinction coefficient, and reflectivity from infrared to ultraviolet, utilizing the dipole-transition theorem for semiconductors. The optical spectra for 8- and 16-ZSiNRs may be classified into two types of the transitions,one between valence and conduction subbands with the same parity, and the other among the edge state and bulk state subbands. With the increase of the ribbon width, the optical spectra for ZSiNRs are proved to exhibit red shift and blue shift at the lower and higher energy regimes, respectively. The obtained novel features are believed to be of significance in designs of silicene-based optoelectronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574051 and 11874117)Natural Science Foundation of Shanghai,China(Grant No.21ZR1408200).
文摘The successfully experimental fabrication of two-dimensional Te monolayer films[Phys.Rev.Lett.119106101(2017)]has promoted the researches on the group-VI monolayer materials.In this work,the electronic structures and topological properties of a group-VI binary compound of TeSe_(2) monolayers are studied based on the density functional theory and Wannier function method.Three types of structures,namely,a-TeSe_(2),b-TeSe_(2),and g-TeSe_(2),are proposed for the TeSe_(2) monolayer among which the a-TeSe_(2) is found being the most stable.All the three structures are semiconductors with indirect band gaps.Very interestingly,the g-TeSe_(2) monolayer becomes a quantum spin Hall(QSH)insulator with a global nontrivial energy gap of 0.14 eV when a 3.5%compressive strain is applied.The opening of the global band gap is understood by the competition between the decrease of the local band dispersion and the weakening of the interactions between the Se px,py orbitals and Te px,py orbitals during the process.Our work realizes topological states in the group-VI monolayers and promotes the potential applications of the materials in spintronics and quantum computations.
