Optical Control of Magnetic Orientation in Epitaxial CoFe₂O₄ Films

Complex oxides have caught significant attention for the development of the next-generation electronic devices due to their versatile functionalities and the tunability via the external stimuli, such as electrical and magnetic fields. To broaden the application of complex oxides, the new pathway to control the physical properties is on demand. Cobalt ferrite (CoFe₂O₄, CFO), a ferrimagnetic inverse spinel, which has advantages of high magnetization and coercivity for magnetic data storage, is investigated in this study. We introduce the high density laser to illuminate the epitaxial CFO film and control the magnetic orientation of the film at ambient temperature. Effects of various illumination conditions of CW and pulsed lasers are systematically investigated. Magnetic force microscopy (MFM) and X-ray magnetic circular dichroism coupled to photoemission electron microscopy (XMCD-PEEM) are used to investigate the magnetic orientation of the optical-modulated area. The possible mechanism for modulating magnetic structures is thus determined as the thermal effect combined with magnetostatic couplings.