Effect of electron correlations on the electronic and magnetic structure of Ti-doped α-hematite -: art. no. 174429

We study the electronic and magnetic structure of alpha-hematite and alpha-hematite doped with Ti using density-functional theory. We use both the local spin-density approximation (LSDA) and the local spin-density approximation with Coulomb correlation (LSDA+U) approximations. We find that as the value of the parameter U is increased, alpha-hematite(Ti) changes from a magnetic half metal with a single relatively delocalized d electron per Ti to an insulator which has the electron localized on a particular Fe site neighboring the Ti impurity. In contrast to Ti-doped alpha-hematite, LSDA and LSDA+U are in qualitative agreement for the undoped system, although LSDA+U predicts values of the structural parameters, band gap, and magnetic moments on the Fe sites which are closer to experimental estimates. In general, LSDA+U appears to be better suited for this type of material.