Ab-initio electronic structure simulations of transition metal doped Bi2Se3 topological insulator

Abstract Induction of ferromagnetism in topological insulators (TI) by transition metal (TM) ion doping has emerged out to be important both from technological point of view and for experimental verification of exotic fundamental physical concepts. Contradicting reports available in the literature on the effect of TM doping on properties of TI's incite the need for further theoretical and experimental works in this field. In the present manuscript, density functional theory based ab-initio theoretical simulations have been carried out on 3d TM (V, Cr, Mn, Fe, Co & Ni) doped TI of Bi2Se3 using the Quantum Espresso code. We have studied the structural changes in Bi2Se3 lattice upon doping by transition metals, stability of the doped materials has been tested by calculating formation energies, subsequently, the magnetic properties of the samples have been investigated and finally, we have simulated the bulk electronic band structure of doped Bi2Se3 topological insulator. Alongwith substitutional doping, we have also investigated the effect of interstitial doping in the bulk band structure of the samples, the report of which is scanty in the literature. The results have been compared vis-a-vis similar reports available in the literature. As a new finding we have shown that interstitial doping of TM ions in Bi2Se3 make it a n-type semiconductor.