Electronic structure and x-ray magnetic circular dichroism in Mn-doped topological insulators Bi2Se3 and Bi2Te3

We studied the structural, electronic, and magnetic properties of Mn-doped topological insulators Bi2Se3 and Bi2Te3 within the density-functional theory (DFT) using the generalized gradient approximation (GGA) in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. The x-ray absorption spectra (XAS) and x-ray magnetic circular dichroism at the Mn K and L-2,L-3 edges were investigated theoretically from first principles. The calculated results are in good agreement with experimental data. The complex fine structure of the Mn L-2,L-3 XAS in Mn-doped Bi2Se3 and Bi2Te3 was found to be not compatible with a pure Mn3+ valency state. Its interpretation demands mixed valent states. The theoretically calculated x-ray emission spectra at the Mn K and L-2,L-3 edges are also presented and analyzed.