Propriedades eletrônicas e topológicas de isolantes topológicos com defeitos pontuais

Abstract

In this work, we have studied the effects of point defects on the electronic and topological properties of a two-dimensional topological insulator (bismuthene). This research is based on first principles calculations using the Density Functional Theory (DFT) with a Generalized Gradient Approximation (GGA), and the Hubbard correction in one of the doped structure. In bismuthene, we investigated the effects caused by substitution of a single Bismuth atom by: a Tin atom (Sn), a Tellurium atom (Te) and a Vanadium (V) atom, p-type, n-type and magnetic doping respectively, 5.5% of defect for each system. In all scenarios the inversion symmetry was broken, so to calculate the topological invariant it was used Wannier Charge Centers (WCC). For all the systems we verified that topological phase is maintained. To identify the edge states behavior, we construct a nanoribbon with the impurity near to one of the edges. For non-magnetic (Sn and Te) defects, the states from impurities interacts with the metalic states and moves the Dirac point to different energy values in comparasion with the undoped edge. The magnetization of V, which is out-of-plane, leads a band-gap opening at the Dirac cones in two different configuration studied in this work, V near and far away to the edge. We also analyzed the spin texture of conduction channels and the <Sz> component showed to be dominant in all cases, but with some peculiar caracteristics when V is near to an edge.