Fabrication and characterization of novel Heusler-type topological insulator thin films

一些半-Heusler合金被预测为拓扑绝缘体(TIS)。半Heusler TiS薄膜是理想的薄膜，因为单轴晶格扭曲会导致表面态的出现，从而在费米能级上打开一个能隙。由于有序/无序结构会导致价带电子结构的显著变化，因此在半-Heusler薄膜中要获得预期的性能必须非常注意有序/无序结构。在本研究中，我们成功地在单晶衬底上生长了高阶参数的外延半Heusler LaPtBi薄膜。价带紫外光电子光谱显示了清晰的结构，与计算的半Heusler LaPtBi的能带结构符合得很好。高阶参数为0.94的样品表现出低的载流子密度和高的迁移率。所获得的LaPtBi薄膜具有潜在的拓扑绝缘器件的应用前景。

Some half-Heusler alloys were predicted to act as topological insulators (TIs). Thin films of half-Heusler TIs are desired as the surface states are expected to arise by introducing uniaxial lattice distortion which opens a gap at the Fermi energy. Great care should be taken to the order/disorder structures to obtain the expected properties in half-Heusler thin films, since the disorder structures lead significant changes of the valence band electronic structures. In this research, epitaxial half-Heusler LaPtBi thin films with high order parameter were successfully grown on single crystalline substrate. Valence band ultraviolet photoelectron spectra exhibited clear structures that are in good agreement with the calculated band structure of half-Heusler LaPtBi. The sample with high order parameter of 0.94 exhibits the low carrier density and the high mobility. The obtained LaPtBi thin films are potential candidates for applications for topological insulator devices.