In order to clarify the controversial issue of the topological nature in a mixed-valent Kondo system, ${\mathrm{SmB}}_6$, we have explored the surface states on the nonpolar (110) surface of ${\mathrm{SmB}}_6$, employing both angle-resolved photoemission spectroscopy (ARPES) experiment and ab initio density-functional theory (DFT) band calculations. Based on ARPES spectroscopic fingerprints and the DFT surface band structures, we ascribe the observed spectral weights at $\overline{X}$ and $\overline{Y}$ on the (110) surface Brillouin zone to topological surface states (TSSs) of “topological insulator (TI)” nature and of “topological crystalline insulator (TCI)” nature, respectively. With varying the chemical potential, the double Dirac cones of the TCI nature exhibit a Lifshitz transition of Fermi surfaces with intriguing spin textures. We have also examined the TSSs on the nearly nonpolar (111) surface of ${\mathrm{SmB}}_6$ in connection with a recently reported ARPES result and proposed a way to probe the Dirac points that are buried in the bulk-projected bands.

中文翻译：

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SmB6的非极性（110）和（111）表面上的拓扑表面状态

为了弄清混合价Kondo系统中拓扑性质的争议性问题， ${\mathrm{小型企业}}_6$，我们已经探索了非极性（110）表面上的表面状态 ${\mathrm{小型企业}}_6$，同时使用角度分辨光发射光谱（ARPES）实验和从头算密度函数理论（DFT）谱带计算。基于ARPES光谱指纹图和DFT表面带结构，我们将观察到的光谱权重归因于$\overline{X}$ 和 $\overline{ÿ}$在（110）表面的布里渊区上，分别具有“拓扑绝缘体（TI）”性质和“拓扑晶体绝缘体（TCI）”性质的拓扑表面状态（TSSs）。随着化学势的变化，TCI性质的双狄拉克锥表现出费米表面的Lifshitz跃迁，并具有有趣的自旋纹理。我们还检查了近非极性（111）表面上的TSS。${\mathrm{小型企业}}_6$ 结合最近报道的ARPES结果，并​​提出了一种探查埋在整体投影带中的狄拉克点的方法。