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 NiCo2O4 (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.