Dual topology modulated Dirac electron transports 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 topological super-lattices (TSLs) with dual topology, Bi₂Se₃-(Bi₂/Bi₂Se₃)_N with limited topological layers N. Angle resolved photoelectron emission spectroscopy (ARPES) demonstrates the coexistence of surface states from the topological insulator (TI) and topological crystalline insulator (TCI) on the Bi₂Se₃ facet. Further, the stacking-sequence dependent quantum transport experiments reveal the unconventional weak antilocalization effect (WAL) with WAL coefficient larger than 1<!--[if gte msEquation 12]> style='mso-bidi-font-style:normal'>a>1, confirming the existence and tunability of spin polarized dual-topological bands on the Bi₂Se₃ facet. Most importantly, we identify the spin polarized surface electrons from dual topological bands exhibit circularly and linearly polarized photo-galvanic effect(C,LPGE) simultaneously under polarized light illumination when excited surface electrons are mutually coupled. Our results shed light on studies of this dual topological class with distinguished topological manifestations coexisting on one facet and multiple topological phases engineering for opto-electronic/spintronic applications.