Single‐Shot Multi‐Level All‐Optical Magnetization Switching Mediated by Spin Transport

TLDR

All‑optical ultrafast magnetization switching in magnetic thin films without external magnetic fields is being explored for ultrafast, energy‑efficient storage, but until now only GdFeCo ferrimagnetic films have shown single‑pulse switching. The study demonstrates that femtosecond light pulses can reversibly switch Co/Pt multilayers in a [Co/Pt]/Cu/GdFeCo spin‑valve, with the ferromagnetic layer’s final state governed by spin‑polarized currents generated by the pulse interaction with GdFeCo, enabling deterministic multi‑bit switching and expanding the range of materials for all‑optical magnetization control.

Abstract

All-optical ultrafast magnetization switching in magnetic material thin film without the assistance of an applied external magnetic field is explored for future ultrafast and energy-efficient magnetic storage and memories. It is shown that femtosecond (fs) light pulses induce magnetization reversal in a large variety of magnetic materials. However, so far, only GdFeCo-based ferrimagnetic thin films exhibit magnetization switching via a single optical pulse. Here, the single-pulse switching of Co/Pt multilayers within a magnetic spin-valve structure ([Co/Pt]/Cu/GdFeCo) is demonstrated and four possible magnetic configurations of the spin valve can be accessed using a sequence of single fs light pulses. The experimental study reveals that the magnetization final state of the ferromagnetic [Co/Pt] layer is determined by spin-polarized currents generated by the light pulse interactions with the GdFeCo layer. This work provides an approach to deterministically switch ferromagnetic layers and a pathway to engineering materials for opto-magnetic multi-bit recording.