We investigate the electronic and magnetic structure of transition-metal-doped $\alpha$-hematite using the local density approximation with local correlations $(\mathrm{LDA}+U)$. The dopants in this study are the $3d$ transition metals $\mathrm{Sc}\text{−}\mathrm{Zn}$ and Ga and are assumed to substitute on an Fe site. The calculated net moment per substitutional impurity is found to be $\mid z_D-z_{\mathit{Fe}}\mid$, opposite to that of the replaced Fe, where $z_D$ and $z_{\mathit{Fe}}$ are the numbers of valence electrons of the dopant and Fe, respectively. The dopants, D, substitute in an effective charged state ${\mathrm{D}}^{3+}$ except for ${\mathrm{Ti}}^{4+}$ and ${\mathrm{Zn}}^{2+}$. In the case of Ti, the extra electron converts a neighboring ${\mathrm{Fe}}^{3+}$ atom to ${\mathrm{Fe}}^{2+}$. 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.

• Received 9 October 2004

DOI:https://doi.org/10.1103/PhysRevB.71.205208