Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
Phys Rev Lett. 2014 Apr 4;112(13):136802. doi: 10.1103/PhysRevLett.112.136802. Epub 2014 Apr 1.
Electron scattering in the topological surface state (TSS) of the topological insulator Bi1.5Sb0.5Te1.7Se1.3 was studied using quasiparticle interference observed by scanning tunneling microscopy. It was found that not only the 180° backscattering but also a wide range of backscattering angles of 100°-180° are effectively prohibited in the TSS. This conclusion was obtained by comparing the observed scattering vectors with the diameters of the constant-energy contours of the TSS, which were measured for both occupied and unoccupied states using time- and angle-resolved photoemission spectroscopy. The robust protection from backscattering in the TSS is good news for applications, but it poses a challenge to the theoretical understanding of the transport in the TSS.
使用扫描隧道显微镜观察到的准粒子干涉，研究了拓扑绝缘体 Bi1.5Sb0.5Te1.7Se1.3 的拓扑表面态（TSS）中的电子散射。结果发现，不仅 180°背散射，而且在 TSS 中有效禁止了 100°-180°的大范围背散射角。这一结论是通过将观察到的散射矢量与 TSS 的等能轮廓的直径进行比较而得出的，这些直径是使用时间和角度分辨光发射光谱法测量的占据和非占据态的。TSS 中背散射的强保护对应用来说是个好消息，但对 TSS 中输运的理论理解提出了挑战。
