Electronic structure and x-ray magnetic circular dichroism in cr-doped topological insulator bi(2)se(3)

We have studied the structural, electronic, and magnetic properties of the Cr-doped topological insulator Bi2Se3 within the density functional theory using the generalized gradient approximation in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. The X-ray absorption spectra and X-ray magnetic circular dichroism at the Cr K and L-2,L-3 edges have been investigated theoretically from the first principles. The calculated results are in good agreement with the experimental data. The complex fine structure of the Cr L-2,L-3 X-ray absorption spectra in Cr-doped Bi2Se3 has been found to be not compatible with a Cr2+ valency state. Its interpretation demands a mixed valent state.