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

Abstract

High-quality MoFe 2 O 4 epitaxial films, exhibiting p-type conductivity and room-temperature ferrimagnetism, were successfully fabricated by a pulsed laser deposition technique. In this experiment, the MoFe 2 O 4 and MoFe 2 O 6 targets prepared via a vacuum-sealed annealing and air annealing were used. The result shows that the spinel MoFe 2 O 4 epitaxial films are obtained by using the MoFe 2 O 4 target, while films with cation-vacant spinel structures exhibiting n-type conductivity are obtained by using the MoFe 2 O 6 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 Mo 3+ ions. The MoFe 2 O 4 film shows room-temperature ferrimagnetism with a large in-plane magnetic anisotropy (5 × 10 5 erg/cm 3 ) and high saturation magnetization (0.7 μ 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 MoFe 2 O 4 is derived from the holes generated in the occupied Mo 3+ 4d 3 t 2g majority spin orbitals. Article pubs.acs.org/crystal

Non-auxetic/auxetic transitions inducing modifications of the magnetic anisotropy in CoFe2O4 thin films

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