Dual Topology of Dirac Electron Transport and Photo-galvanic Effect in Low-dimensional Topological Insulator Superlattices.

Dual topological insulators, simultaneously protected by time-reversal symmetry and crystalline symmetry, open great opportunities to explore different symmetry-protected metallic surface states. However, the conventional dual topological states located on different facets hinders integration into planar opto-electronic/spintronic devices. Here, we construct dual topological superlattices (TSLs) Bi 2 Se 3 -(Bi 2 /Bi 2 Se 3 ) N with limited stacking layer number N. Angle-resolved photoelectron emission spectra of the TSLs identify the coexistence and adjustion of dual topological surface states on Bi 2 Se 3 facet. The existence and tunability of spin-polarized dual-topological bands with N on Bi 2 Se 3 facet result in an unconventionally weak antilocalization effect (WAL) with variable WAL coefficient α (maximum close to 3/2) from quantum transport experiments. Most importantly, we identify the spin-polarized surface electrons from dual topological bands exhibit circularly and linearly polarized photo-galvanic effect (CPGE and LPGE). We anticipate that the stacked dual-topology and stacking layer number controlled bands evolution provide a platform for realizing intrinsic CPGE and LPGE. Our results show that the surface electronic structure of the dual TSLs is highly tunable and well-regulated for quantum transport and photoexcitation, which shed light on engineering for opto-electronic/spintronic applications. This article is protected by copyright. All rights reserved.