Zhao Bao, Zhang Jiayong, Wang Yicheng, Yang Zhongqin
State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) and Department of Physics, Fudan University, Shanghai 200433, China.
J Chem Phys. 2014 Dec 28;141(24):244701. doi: 10.1063/1.4904285.
The electronic states and topological behaviors of Pt(Ni, Pd)-decorated silicene are investigated by using an ab-initio method. All the three kinds of the adatoms prefer hollow sites of the silicene, guaranteeing the Dirac cones unbroken. The Pt(Ni, Pd)-decorated silicene systems all present quantum valley Hall (QVH) states with the gap opened exactly at the Fermi level. The gaps of the QVH states can be increased substantially by applying a positive electric field. Very fascinating phase transitions from QVH to quantum spin Hall (QSH) and then to QVH again are achieved in the Pt/Ni-decorated silicene when a negative electric field is applied. The QSH state in the Pd case with a negative electric field is, however, quenched because of relatively larger Rashba spin-orbit coupling (SOC) than the intrinsic SOC in the system. Our findings may be useful for the applications of silicene-based devices in valleytronics and spintronics.
采用第一性原理方法研究了Pt（Ni，Pd）修饰的硅烯的电子态和拓扑行为。所有这三种吸附原子都倾向于硅烯的中空位点，从而保证狄拉克锥的完整性。Pt（Ni，Pd）修饰的硅烯体系均呈现量子谷霍尔（QVH）态，其能隙恰好于费米能级处打开。通过施加正电场可大幅增加QVH态的能隙。当对Pt/Ni修饰的硅烯施加负电场时，会实现从QVH到量子自旋霍尔（QSH）再回到QVH的非常有趣的相变。然而，在施加负电场的情况下，由于体系中相对较大的Rashba自旋轨道耦合（SOC）大于本征SOC，Pd情况下的QSH态会被淬灭。我们的研究结果可能对基于硅烯的器件在谷电子学和自旋电子学中的应用有用。
