TY - JOUR
T1 - Four-band tight-binding model of TiSiCO-family monolayers
AU - Cui, Chaoxi
AU - Han, Yilin
AU - Zhang, Ting Ting
AU - Yu, Zhi Ming
AU - Yao, Yugui
N1 - Publisher Copyright:
© 2023 American Physical Society.
PY - 2023/10/15
Y1 - 2023/10/15
N2 - The TiSiCO-family monolayers have recently been attracting significant attention due to their unique valley-layer coupling (VLC). In this work, we present a minimal, four-band tight-binding (TB) model to capture the low-energy physics of the TiSiCO-family monolayers Z2YCO2 (Z=Ti, Zr, Hf; Y=Si, Ge) with strong VLC. These monolayers comprise two Z atom layers separated by approximately 4 Å in the out-of-plane direction. Around each valley (X or X′), the conduction and valence bands are mainly dominated by the A1{dz2(x2-y2)} and B2{dyz} orbitals of the top Z atoms, and the A1{dz2(x2-y2)} and B1{dxz} orbitals of the bottom Z atoms. Using these four states as a basis, we construct a symmetry-allowed TB model. Through parameter fitting from first-principles calculations, the four-band TB model not only reproduces the electronic band structure, but also captures the strong VLC, high-order topology, and valley-contrasting linear dichroism of the monolayers. Furthermore, the TB model reveals that these monolayers may exhibit various intriguing topological phases under electric fields and biaxial strains. Hence, the TB model established here can serve as the starting point for future research exploring the physics related to VLC and the Z2YCO2 monolayers.
AB - The TiSiCO-family monolayers have recently been attracting significant attention due to their unique valley-layer coupling (VLC). In this work, we present a minimal, four-band tight-binding (TB) model to capture the low-energy physics of the TiSiCO-family monolayers Z2YCO2 (Z=Ti, Zr, Hf; Y=Si, Ge) with strong VLC. These monolayers comprise two Z atom layers separated by approximately 4 Å in the out-of-plane direction. Around each valley (X or X′), the conduction and valence bands are mainly dominated by the A1{dz2(x2-y2)} and B2{dyz} orbitals of the top Z atoms, and the A1{dz2(x2-y2)} and B1{dxz} orbitals of the bottom Z atoms. Using these four states as a basis, we construct a symmetry-allowed TB model. Through parameter fitting from first-principles calculations, the four-band TB model not only reproduces the electronic band structure, but also captures the strong VLC, high-order topology, and valley-contrasting linear dichroism of the monolayers. Furthermore, the TB model reveals that these monolayers may exhibit various intriguing topological phases under electric fields and biaxial strains. Hence, the TB model established here can serve as the starting point for future research exploring the physics related to VLC and the Z2YCO2 monolayers.
UR - http://www.scopus.com/inward/record.url?scp=85175013619&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.108.155115
DO - 10.1103/PhysRevB.108.155115
M3 - Article
AN - SCOPUS:85175013619
SN - 2469-9950
VL - 108
JO - Physical Review B
JF - Physical Review B
IS - 15
M1 - 155115
ER -