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

• Published in: Crystal growth & design 2019-02, Vol.19 (2), p.902-906
• Main Authors: Katayama, Tsukasa, Kurauchi, Yuji, Mo, Shishin, Gu, Ke, Chikamatsu, Akira, Galiullina, Lyaysan, Hasegawa, Tetsuya
• Format: Article
• Language: eng ; jpn
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.8b01454

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 × 105 erg/cm3) and high saturation magnetization (0.7 μB/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+ 4d3 t2g majority spin orbitals.