All-Optical Magnetic Recording with Circularly Polarized Light

Abstract

We experimentally demonstrate that the magnetization can be reversed in a reproducible manner by a single 40 femtosecond circularly polarized laser pulse, without any applied magnetic field. This optically induced ultrafast magnetization reversal previously believed impossible is the combined result of femtosecond laser heating of the magnetic system to just below the Curie point and circularly polarized light simultaneously acting as a magnetic field. The direction of this opto-magnetic switching is determined only by the helicity of light. This finding reveals an ultrafast and efficient pathway for writing magnetic bits at record-breaking speeds.

Nanoscale spin reversal by non-local angular momentum transfer following ultrafast laser excitation in ferrimagnetic GdFeCo

“…Therefore, the laser fluence used was 24 mJ/cm 2 , significantly higher than that used to observe transient ferromagnetism 4.4 mJ/cm 2 (ref. (8) from the main paper), or all-optical switching of 2.9 mJ/cm 2 (13). We note that for the laser fluence 24 mJ/cm 2 the equilibrium sample temperature after 1-2 ps will be above the magnetic ordering temperature.…”

Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current

“…This ultrafast demagnetization is then followed by a slower magnetization recovery on picosecond timescales. Optically induced magnetization reversal has also been demonstrated using circularly polarized light 4 . A number of distinct models have been proposed to describe how laser excitation can couple so quickly to the spins, given that the light itself does not directly exert a significant torque on the electron spins.…”

Laser-induced ultrafast demagnetization in the presence of a nanoscale magnetic domain network

“…Additionally, it has attracted considerable interest as a possible path to magnetization control on a femtosecond timescale 3 . Most commonly, the magneto-optical Kerr effect (MOKE) is exploited as a femtosecond probe of the temporal evolution of magnetization 2 .…”