半Heusler型拓扑绝缘体LaPtBi能带调控的研究

摘要

Using the full-potential linearized augmented plane-wave method based on the density functional theory, we investigate the influences of chemical substitution and uniaxial strain on the topological electronic structure of the half-Heusler compound LaPtBi. It is shown that the/78 band which is protected by the cubic symmetry of the Clb structure can open and form a gap by substituting Sc element for La or Pd for Pt in LaPtBi compound. However, in the case of distorting cubic lattice by using a uniaxial strain, not only the gap mentioned above appears, but also the Fermi level can be tuned regularly. Thus the LaPtBi compound becomes a real topological insulator.%采用基于密度泛函理论的全势能线性缀加平面波的方法，研究了化学替代和施加等体积单轴（拉、压）应力两种方式对半Heusler型拓扑绝缘体LaPtBi能带的影响．计算结果表明，通过在LaPtBi合金中用Sc元素替换La，或者用Pd替换Pt，都可以使得原本受立方对称性保护的几能带在费米能级附近打开一带隙；而对于施加等体积单轴应力来扭曲立方晶格的方式，在使得几能带打开的同时，还可以实现对费米能级位置有规律地调控，使LaPtBi合金最终成为真正意义上的体材料是绝缘性而表面是金属性的拓扑绝缘体．