Abstrakt
Spintronics represents a possible route to solve the increasing demands on the computational devices. One of the possible materials to use there are time reversal symmetry protected topological insulators (TRS TI).
They host linearly dispersed spinpolarized states on their surfaces, which makes the surface band structure gapless. Whereas in the bulk a band gap is kept.
The occurrence of surface conductive states, so-called 'Dirac states', is based on the presence of a strong spin-orbit coupling leading to the inverted parity of surface valence and conductive states, where the TRS is kept. In our study we focus on properties of well known bismuth chalcogenides under a chemical and structural disorder, which includes native point defects, stacking faults and magnetic doping as well.
The inclusion of native defects is important to the real description of the TIs behavior in the comparison to experiments. Besides, magnetic defects can serve to control the transport behavior by breaking TRS.
Using ab-initio TB-LMTO-ASA calculation within the layered Green's functions formalism we studied the resistance of gapless surface state to the presence of the disorder. The inclusion of native and magnetic defects in studied layered structures was treated by CPA.
We will discussed induced modification of the surface band structure and the influence on the transport properties. The critical concentration for magnetic doping leading to the vanishing surface conductivity will be shown.
Finally we compare how realistic are our calculations in comparison to the experiments