Lee Kyu Won, Lee Cheol Eui
Department of Physics, Korea University, Seoul, 02841, Republic of Korea.
Sci Rep. 2020 Mar 19;10(1):5044. doi: 10.1038/s41598-020-61906-2.
We have investigated the valley Chern number and gapless edge states in wide-gap semiconductor SiC and BN monolayers by using the density functional theory calculations. We found that while SiC monolayer has a non-quantized valley Chern number due to a partial mixing of the Berry curvature peaks pertaining to the opposite valleys, there exist topologically protected gapless edge states within the bulk gap, leading to a quantum valley Hall effect. Doping of the opposite charge carriers causes a backscattering-free valley current flowing on the opposite edge, which can be used for experimental confirmation and application at room temperature. BN monolayer, on the other hand, was found to have gapped edge states due to the too large staggered AB-sublattice potentials.
我们通过密度泛函理论计算研究了宽禁带半导体碳化硅（SiC）和氮化硼（BN）单层中的谷陈数和无隙边缘态。我们发现，由于与相反谷相关的贝里曲率峰部分混合，SiC单层具有非量子化的谷陈数，但其体能隙内存在拓扑保护的无隙边缘态，从而导致量子谷霍尔效应。相反电荷载流子的掺杂会使无背散射的谷电流在相反边缘流动，这可用于室温下的实验验证和应用。另一方面，由于交错的AB子晶格势过大，BN单层被发现具有带隙边缘态。
