Characterization of magnetic properties of ultrathin CoFe2O4 films by utilizing magnetic proximity effect. (February 2020)

• Record Type: Journal Article
• Authors: Nodo, S.; Yamamoto, T.; Yanase, T.; Shimada, T.; Nagahama, T.
• Is Part Of: Solid state communications. Volume 306(2020)
• Publication Date: 2020-02
• Subjects: Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2019.113762
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: Magnetic spinel oxides, including CoFe2 O4 (CFO), have crucial applications in spintronics. They have excellent magnetic properties, such as high spin polarization and high Curie temperature, which enables the operation of spintronic devices at room temperature. Some interesting phenomena have also been discovered for interfaces consisting of spinel oxides and heavy metals. However, the magnetic properties of ultrathin CFO films have not been investigated sufficiently. In this report, a characterization of the magnetic properties of an ultrathin CFO film was performed by using the magnetic proximity effect (MPE) to observe the anomalous Hall effect (AHE) in Pt. The result was consistent with the measurement performed with magneto-optical effects. By fitting AHE with the Langevin function, it was concluded that these ultrathin films ( t CFO <3.4 nm) showed superparamagnetism, and the magnetic moment was estimated to be 3000μB . The results provided the novel method to evaluate the magnetic properties of ferromagnetic insulators by using MPE and AHE, thus providing a better understanding of interface magnetism. Highlights: We succeeded in observation of the anomalous Hall effect in Pt due to a magnetic proximity effect at an interface of Pt/CoFe2 O4 . The remanent ratio and the coercivity of Hall effect strongly depended on the temperature and thickness of CoFe2 O4 . The magnetic field dependence of the Hall effect could be understood by superparamagnetism of CoFe2 O4 .