论文标题
薄膜拓扑绝缘子中的间隙零锥和旋转质地
Gapped Dirac cones and spin texture in thin film topological insulator
论文作者
论文摘要
拓扑绝缘子（TIS）的受保护的表面状态形成与螺旋自旋极化相应的非脱位本征的无间隙狄拉克锥。像BI2SE3和BI2TE3中一样，翘曲项的存在将最简单模型的各向同性锥变形为雪花费米表面。它们的特征已在孤立表面上的STM准颗粒干扰（QPI）实验中鉴定出来。在这里，我们研究了Ti薄膜几何形状的QPI频谱，并在表面状态之间进行有限的隧穿。这会导致由于间隙的间隙和旋转质地的变化而引起的频谱的急剧变化，该纹理应在QPI模式中留下不同的签名。我们考虑从表面杂质的正常和磁交换散射，并在天生的近似以及一般闭合溶液中获得散射T-Matrix。我们通过改变膜的厚度和研究，特别是对反向散射过程的影响，显示了QPI雪花强度特征的预期系统变化。我们使用ARPES结果观察到的间隙依赖性预测BI2SE3薄膜的QPI光谱的变化。
The protected surface states of topological insulators (TIs) form gapless Dirac cones corresponding non-degenerate eigenstates with helical spin polarisation. The presence of a warping term deforms the isotropic cone of the most simple model into snowflake Fermi surfaces as in Bi2Se3 and Bi2Te3. Their features have been identified in STM quasiparticle interference (QPI) experiments on isolated surfaces. Here we investigate the QPI spectrum for the TI thin-film geometry with finite tunnelling between the surface states. This leads to a dramatic change of spectrum due to gapping and a change in spin texture that should leave distinct signatures in the QPI pattern. We consider both normal and magnetic exchange scattering from the surface impurities and obtain the scattering t-matrix in Born approximation as well as the general closed solution. We show the expected systematic variation of QPI snowflake intensity features by varying film thickness and study, in particular, the influence on backscattering processes. We predict the variation of the QPI spectrum for Bi2Se3 thin films using the observed gap dependence from ARPES results.
