p-Type Conductivity and Room-Temperature Ferrimagnetism in Spinel MoFe2O4 Epitaxial Thin Film

High-quality MoFe2O4 epitaxial films, exhibiting p-type conductivity and room-temperature ferrimagnetism, were successfully fabricated by a pulsed laser deposition technique. In this experiment, the MoFe2O4 and MoFe2O6 targets prepared via a vacuum-sealed annealing and air annealing were used. The result shows that the spinel MoFe2O4 epitaxial films are obtained by using the MoFe2O4 target, while films with cation-vacant spinel structures exhibiting n-type conductivity are obtained by using the MoFe2O6 target even under reductive deposition conditions. Thus, controlling the oxygen content in the target is crucial to realize p-type conductivity probably related to the requirement of highly reductive Mo3+ ions. The MoFe2O4 film shows room-temperature ferrimagnetism with a large in-plane magnetic anisotropy (5 x 10(5 )erg/cm(3)) and high saturation magnetization (0.7 mu(B)/f.u.). In addition, the film exhibits an anomalous Hall effect and magnetoresistance at room temperature. Density functional theory calculations reveal that the p-type conductivity of MoFe2O4 is derived from the holes generated in the occupied Mo3+ 4d(3) t(2g) majority spin orbitals.