Structure and magnetism of Fe-doped BaSnO3 thin films

Abstract

BaSnO3 is an excellent candidate system for developing a new class of perovskite-based dilute magnetic semiconductors. In this study, we show that BaSn0.95Fe0.05O3 can be grown from a background pressure of ∼2×10−3 mTorr to oxygen pressures of 300 mTorr with high crystallinity and excellent structural quality. When grown in vacuum, the films may be weakly ferromagnetic with a nonzero x-ray magnetic circular dichroism signal on the Fe L3 edge. Growth with oxygen flow appears to suppress magnetic ordering. Even for very thick films grown in 100 mTorr O2, the films are paramagnetic. The existence of ferromagnetism in vacuum-grown BaSnO3 may be attributed to the F-center exchange mechanism, which relies on the presence of oxygen vacancies to facilitate the ferromagnetism. However, other possible extrinsic contributions to the magnetic ordering, such as clusters of Fe3O4 and FeO or contamination can also explain the observed behavior.