Accumulative Magnetic Switching of Ultrahigh-Density Recording Media by Circularly Polarized Light

Magnetization control of ferromagnetic materials only by circularly polarized light has received increasing attention both as a fundamental probe of the interactions of light and magnetism but also for future highdensity magnetic recording technologies. Here we show that for granular FePt films designed for ultrahighdensity magnetic recording, the optical magnetic switching by circularly polarized light is an accumulative effect from multiple optical pulses. The measured results can be reproduced by a simple statistical model where the probability of switching a grain depends on the helicity of the optical pulses.We further show the deterministic switching of high-anisotropy materials by the combination of circularly polarized light and modest external magnetic fields, thus, revealing a pathway towards technological implementation.