Estudo de isolantes topológicos derivados da jacutingaita

Abstract

In this work we have investigated the electronic and topological properties of the mineral Pt2HgSe3, known as Jacutingaite, and also of materials derived from this one, such as Ir2HgSe3, Co2HgSe3, Ni2HgSe3, among others with less concentration of the atoms Ir, Co and Ni. This work was realized within the Density Functional Theory(DFT) framework with the objective of determine the properties of the fundamental state of these materials. The Jacutingaite has a very complex Fermi surface, which led us to realize electronic and hole dopping with the objective of vary the Fermi level and possibly induce electronic instabilities throught the nesting fenomena. Our results shows that these dopping directly affects the gap opening on the high symmetry points of the Brillouin zone K and H, when compared to the pristine form of Jacutingaite. In special, for the electron dopping we have observed a decrease of up to three times on the H gap, and in the case of hole dopping we have observed a increase on the electron pockets at the Fermi level. Furthermore for a specific value of dopping we have not observed the occurency of band inversion, which show us that the system has lost its topological phase due to the removal of charge. We have also performed atomic substituition of both species of platina for nickel, iridium and cobalt. The electronic, structural and topological properties of these systems were investigated and for the promissing materials a maximum localized Wannier functions tight-binding hamiltonian were generated, from which we have obtained the electronic structure of the edges, the topological invariante Z2 and also spectral functions. Our results shows that the topological phase disappear due to the induced magnetism in the system after substituition of a specific specie of platina for nickel. Furthermore we have also observed that a substitution of the other specie of platina for nickel lead to a distinct phase which presents non-topological conducting edge channels. We found that the proposed material Ir2HgSe3 loses its topological phase due to the substitution of platina for iridium, which led to a hexagonal symmetry break of the Brillouin zone. However we have shown that the topological phase can be restored throught physical stress of the structure. The respectives band structures, density of states, Z2 invariante and spectral functions were also obtained.