How disorder affects topological surface states in the limit of ultrathin Bi₂Se₃films

Abstract

We present a first-principles study of electronic properties of ultrathin films of topological insulators and scrutinize the role of disorder on the robustness of topological surface states, which can be analysed through their spin textures. The presence of twin grain boundaries is found to increase the bandgap of the film, while preserving the spin texture of states in first conduction and valence bands. Differently, partial hydrogenation of one surface not only results in some self-doping effect, but also provokes some alteration of the spin texture symmetry of the electronic states. The formation of a new Dirac cone at M -point of the Brillouin zone of the hydrogenated surface, together with a modified spin texture characteristics are consistent with a dominant Dresselhaus spin-orbit interaction type, more usually observed in 3D materials. Our findings indicate that defects can either be detrimental or beneficial for exploring spin transport of surface states in the limit of ultrathin films of topological insulators, which maximizes surface over bulk phenomena.

Heterostructures containing dichalcogenides-new materials with predictable nanoarchitectures and novel emergent properties

“…The stability of CuS 2D layers as a function of thickness was recently reported [297]. The impact of the twist angle between ultrathin layers of Bi 2 Se 3 [298] and the specific arrangement of different cations within a dichalcogenide layer [299] on potential topological states has been explored, as well. Extending these studies to probe potential heterostructures would be useful for experimentalists, and the misfit layer compounds provide an opportunity to compare predictions with experimental data.…”