Optical Modulation of Magnetism in Epitaxial Cobalt Ferrite Thin Films

Yi-De Liou^1*, I-Tse Tsai¹, Yao-Wen Chang¹, Jan-Chi Yang¹, Yi-Chun Chen¹

¹Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Yi-De Liou, email:leave710584@gmail.com

Complex oxides exhibit intriguing functionalities that offer tremendous opportunities to develop next generation electronic devices. Controlling the correlated phenomena by optical methods has been a significant challenge due to the lack of adequate interaction between the order parameter and light. In this work, we explore the optical tunability of ferrimagnetic cobalt ferrite (CoFe₂O₄, CFO) thin film system, which have been reported to be promising candidate materials for technological applications due to their large magnetostriction, high remanence and coercivity at room temperature. Magnetic force microscopy (MFM) is employed to in situ observe the evolution of magnetic domain configuration that is before and after modulation by a focused laser beam. We successfully demonstrate the optical control of magnetic domain structure in CFO films at ambient operating room temperature after comprehensively investigating the impact of fluence, pulse duration, wavelength, and polarization of excitation light source. A model of the photon-induced demagnetization is also proposed to explain the nonvolatile manipulation via light stimulus. Our findings provide novel insights into to the modulation of ferro ordering in complex oxides that offers prospects for optical control of multifunctionalities.

Keywords: optical control, complex oxide, ferrimagnetic, Cobalt ferrite, CoFe₂O₄