Magnetization Switching of L10-FePt Nanoparticles by Combination Effect From Multishot Circularly Polarized Laser Pulses

All-optical magnetic switching observed on some materials provides a potential recording option due to its ultrashort recording time and low-power consumption. In most studies, this phenomenon is attributed to the inverse Faraday effect that a circularly polarized laser will induce an optomagnetic field or magnetic circular dichroism that one magnetization orientation will absorb more energy than another. L10-FePt is a promising candidate for high-density magnetic recording due to its high perpendicular anisotropy, whose magnetization is fixed out of plane either up or down. However, the mechanism about all-optical switching on FePt is still under debate. In this paper, we show that it benefits from both inverse Faraday effect and magnetic circular dichroism. We use an accumulative model to demonstrate the results of an ensemble of single-domain L10-FePt nanoparticles after multishot circularly polarized femtosecond laser pulses. The simulation results agree with the observation results of Lambert et al. and demonstrate the possibility of reaching deterministic all-optical magnetic recording by optimizing the laser fluence and the optomagnetic field strength.