Ubiquity of ferromagnetic signals in common diamagnetic oxide crystals

Phys. Rev. B 81, 214414 (2010)

M. Khalid, A. Setzer, M. Ziese, P. Esquinazi, D. Spemann, A. Pöppl, E. Goering


The magnetic properties of MgO, MgAl2O4, SrTiO3, LaAlO3, LSAT, and ZnO single crystals were investigated. These crystals show three contributions to the magnetization, namely, an intrinsic diamagnetic contribution, a paramagnetic contribution, due to various transition-metal impurities, as well as a ferromagnetic contribution. The latter shows coercive field values that are rather independent of the actual crystal material. The ferromagnetic hysteresis loops of the magnetization per volume suggest a surface contribution. The origin of the ferromagnetic contribution as arising from either defect-induced ferromagnetism or ferromagnetic impurities is discussed.