Electronic and magnetic structure of transition-metal-dopedα-hematite

We investigate the electronic and magnetic structure of transition-metal-doped α-hematite using the local density approximation with local correlations (LDA+U). The dopants in this study are the $3d$ transition metals Sc-Zn and Ga and are assumed to substitute on an Fe site. The calculated net moment per substitutional impurity is found to be zD-zFe, opposite to that of the replaced Fe, where zD and zFe are the numbers of valence electrons of the dopant and Fe, respectively. The dopants, D, substitute in an effective charged state D³⁺ except for Ti⁴⁺ and Zn²⁺. In the case of Ti, the extra electron converts a neighboring Fe³⁺ atom to Fe²⁺. In the case of Zn, the missing electron generates a relatively diffuse hole at the top of the valence band spread over neighboring O atoms.