First-principles calculations to study the electronic and magnetic properties of bulk, oxygen-deficient SrTiO3 (STO) under different doping conditions and densities have been conducted. The appearance of magnetism in oxygen-deficient STO is not determined solely by the presence of a single oxygen vacancy but by the density of free carriers and the relative proximity of the vacant sites. We find that while an isolated vacancy behaves as a non-magnetic double donor, manipulation of the doping conditions allows the stability of a single donor state, with emergent local moments coupled ferromagnetically by carriers in the conduction band. Strong local lattice distortions enhance the binding of this state. The energy of the in-gap local moment can be further tuned by orthorhombic strain. Consequently we find that the free-carrier density and strain are fundamental components to obtaining trapped spin-polarized electrons in oxygen-deficient STO, which may have important implications in the design of optical devices.
@article{arxiv.1408.3103,
title = {Magnetism and metal-insulator transition in oxygen deficient SrTiO$_3$},
author = {Alejandro Lopez-Bezanilla and P. Ganesh and Peter B. Littlewood},
journal= {arXiv preprint arXiv:1408.3103},
year = {2016}
}