2025/11/28 by Jan Skolimowski, Nguyen Minh Nguyen, Skolimowski, Jan +7
Physics and Astronomy · #Topological Materials and Phenomena #Surface and Thin Film Phenomena #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.2511.23289
We formulate the tight-binding model for cubic α-Sn based on the DFT calculations. In the model, we incorporate a variable bond angle, which allows us to simulate the effect of the in-plane strain. In the bulk, we demonstrate the presence of the ℤ2 topological invariant and a non-zero mirror Chern number, making α-Sn one of the rare cases where dual topology can be observed. We calculate the topological phase diagram of multi-layer α-Sn as a function of strain and number of layers. We find that a non-trivial quantum spin Hall state appears only for compressive strain above five layers of thickness. Quite surprisingly, both in the trivial and non-trivial phases, we find a plethora of edge-states with energies inside the bulk gap of the system. Some of these states are localized at the side surfaces of the slab, some of them prefer top/bottom surfaces and some are localized in the hinges. We trace the microscopic origin of these states back to a minimal model that supports chiral symmetry and multiple one-dimensional winding numbers that take different values in different directions in the Brillouin zone.