局域势调控下石墨烯/h-BN异质结的能带结构和量子相变

Band Structure and Quantum Phase Transition of Graphene/h-BN Heterojunction under Local Potential Control

采用紧束缚方法研究了局域势调控下石墨烯/六方氮化硼异质结的能带结构及量子相变。结果表明,在给定石墨烯层内禀自旋轨道耦合强度时,石墨烯层处于量子自旋霍尔态而六方氮化硼层处于绝缘态,增大石墨烯层局域势,系统会从量子自旋霍尔态变到半导体态。调节六方氮化硼层局域势可以使异质结产生新的无间隙边缘态,从而使系统中石墨烯层的量子自旋霍尔态变成由层内和层间的边缘态共同构成的量子自旋霍尔态。

The band structure and quantum phase transition of graphene/hexagonal boron nitride heterojunction (h-BN) under local potentials are studied by the tight-binding method. The result shows that the graphene layer is in the quantum spin Hall state and the h-BN layer is in the insulating state when the intrinsic spin-orbit coupling strength of the graphene layer is given. As the local potential of the graphene layer increases, the system will change from a quantum spin Hall state to a semiconductor state. New gapless edge states can be generated by tuning the local potential of the h-BN layer, so that the quantum spin Hall state of the graphene layer becomes the quantum spin Hall state composed of the edge states within and between layers.