Single shot all optical switching of intrinsic micron size magnetic domains of a Pt/Co/Pt ferromagnetic stack

TL;DR

This study demonstrates that a single femtosecond laser pulse can reversibly switch magnetization in a Pt/Co/Pt ferromagnetic stack, with the process depending on domain size and occurring within microseconds.

Contribution

It reveals that optical switching of ferromagnetic domains can be achieved with single pulses matching intrinsic domain sizes, independent of light helicity.

Findings

Switching occurs with a single femtosecond laser pulse.

The switched spot size matches intrinsic magnetic domains.

Reversal dynamics occur in less than one microsecond.

Abstract

We demonstrate that the magnetization reversal in a ferromagnetic Pt/Co/Pt stack can be induced by a single femtosecond laser pulse. We find that the size of the switched spot is comparable to the size of the intrinsic magnetic domains. It requires an absorbed energy density of $\sim$4 mJ.cm$^{-2}$, beyond which the excited spot fragments into a multidomain structure. The switching process occurs back and forth with subsequent laser pulses and it is helicity-independent. Furthermore, the dynamics of the magnetization reversal occurs in a timescale less than one microsecond. These results suggest that all optical switching in ferromagnetic films requires to match the laser spot with the specific domain sizes.