2022/02/08 by Baokai Wang, Wang, Baokai, Xiaoting Zhou +7 · 2 citations
Materials Science · Physics and Astronomy · #Crystallography and Radiation Phenomena #FOS: Physical sciences #Graphene research and applications #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2202.04162
openalex publication_date 2022/02/08 · openalex created_date 2022/05/05 · openalex updated_date 2026/07/28
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 \rmX-\rmΓ-\rmX 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 Sz-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 Z2 topological insulator. Our study shows that quantized spin Hall conductivity can serve as a topological invariant beyond Z2 for characterizing topological phases.