Quantum valley Hall states in low-buckled counterparts of graphene bilayer

With low-buckled structure for each layer in graphene bilayer system, there breaks inversion symmetry (P-symmetry) for one stacking when both A and B sublattices in top layer are aligned with those in bottom layer. In consideration of spin-orbit coupling (SOC), there opens nontrivial topological gap...

Full description

Saved in:
Bibliographic Details
Published inarXiv.org
Main Authors Yu-Hao, Shen, Jun-Ding, Zheng, Wen-Yi, Tong, Zhi-Qiang Bao, Xian-Gang Wan, Chun-Gang Duan
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 05.08.2024
Subjects
Bilayers
Electromagnetism
Graphene
Quantum Hall effect
Spin-orbit interactions
Symmetry
Topological insulators
Online AccessGet full text

Cover

More Information
Summary:With low-buckled structure for each layer in graphene bilayer system, there breaks inversion symmetry (P-symmetry) for one stacking when both A and B sublattices in top layer are aligned with those in bottom layer. In consideration of spin-orbit coupling (SOC), there opens nontrivial topological gap in each monolayer system to achieve quantum spin Hall effect (QSHE). As long as time-reversal symmetry (T-symmetry) is preserved the gapless edge states is robust in each individual layer even for the bilayer absent of PT symmetry. Based on this platform and through tight-binding (TB) model calculations we find it becomes a typical system that can exhibit quantum valley Hall effect (QVHE) when introduced a layer-resolved Rashba SOC that leads to band inversion at each K valley in the hexagonal Brillion zone (BZ). The topological transition comes from that the valley Chern number Cv = CK - CK' switches from 0 to 2, which characterizes the nontrivial QVHE phase transited from two coupled Z2 topological insulators. We also point that the layer-resolved Rashba SOC can be introduced equivalently by twisting two van der Waals touched layers. And through TB calculations, it is shown that the K bands inverts in its corresponding mini BZ when the two layers twisted by a small angle. Our findings advance potential applications for the devices design in topological valleytronics and twistronics.
ISSN:2331-8422