论文标题
$α$ - 抗乙烯的高旋转核糖绝缘子具有隐藏的拓扑阶段
High Spin-Chern-Number Insulator in $α$-Antimonene with a Hidden Topological Phase
论文作者
论文摘要
在研究单层$α$或相V元素的拓扑电子结构时，我们发现了一个新的拓扑阶段，该阶段在基于对称的拓扑量子化学（TQC）以及对称指标（SIS）中是看不见的。由于$α$ a相和SB在高对称点上共享相同的频带表示，因此在TQC和SI方面，它们都是琐碎的绝缘子。但是，我们证明，AS和SB之间存在拓扑相变，其中涉及在高对称性$ \ rm {x} $ - $ \rmγ$ - $ \rmγ$ - $ \ rm {x} $ line上的带隙关闭。在没有旋转轨道耦合（SOC）的情况下，琐碎的绝缘子也是如此，而SB是一个狄拉克的半学，距离高对称线的四个狄拉克点（DPS）。包括$ s_z $保守的SOC差距脱离狄拉克点，并引起非平凡的浆果曲率，并将SB驱动到高旋转的Chern数字拓扑阶段。 $α$ -bi的频带结构与$γ$的频段反转的SB不同，将BI转换为Z $ _2 $拓扑绝缘子。我们的研究表明，量化的自旋霍尔电导率可以用作表征拓扑阶段的Z $ _2 $以外的拓扑不变。
In investigating the topological electronic structures of monolayer $α$-phase group V elements, we uncover a new topological phase, which is invisible in the symmetry-based topological quantum chemistry (TQC) as well as symmetry indicators (SIs). Since $α$ phase As and Sb share the same band representations at high-symmetry points, they are both trivial insulators in terms of TQC and SIs. We demonstrate, however, that there is a topological phase transition between As and Sb that involves a band-gap closing at two $k$-points on the high-symmetry $\rm{X}$-$\rmΓ$-$\rm{X}$ line. In the absence of spin-orbit coupling (SOC), As is a trivial insulator, while Sb is a Dirac semimetal with four Dirac points (DPs) located away from the high-symmetry lines. Inclusion of $S_z$-conserved SOC gaps out the Dirac points and induces a nontrivial Berry curvature and drives Sb into a high spin Chern number topological phase. The band structure of $α$-Bi differs from that of Sb by a band inversion at $Γ$, transforming Bi into a Z$_2$ topological insulator. Our study shows that quantized spin Hall conductivity can serve as a topological invariant beyond Z$_2$ for characterizing topological phases.
