Optically Induced Magnetization Switching in NiCo₂O₄ Thin Films Using Ultrafast Lasers

All-optical magnetization control has recently been garnering considerable attention to realize next-generation ultrafast magnetic information devices. Here, employing a magneto-optical Kerr effect (MOKE) microscope, we observed the laser-induced magnetization switching of ferrimagnetic oxide NiCo 2 O 4 (NCO) epitaxial thin films with perpendicular magnetic anisotropy, where the sample was pumped by 1030 nm laser pulses, and magnetic domain images were acquired via the MOKE microscope with a white light emitting diode. Laser pulses irradiated the NCO thin film at various temperatures from 300 to 400 K while altering the parameters of pulse interval, fluency, and the number of pulses in the absence of the external magnetic field. We observed accumulative all-optical helicity-dependent switching above 380 K. Our observation of oxide NCO thin films facilitates the realization of magnetization switching using ultrafast lasers without applying a magnetic field.