Optically driven spin pumping mediating collective magnetization dynamics in a spin valve structure

TL;DR

This paper demonstrates optically driven spin pumping in a spin valve structure using femtosecond laser pulses, revealing dynamic, resonant coupling of magnetizations without microwave radiation.

Contribution

It introduces a novel optical method for spin pumping and studies the resulting dynamic coupling in a spin valve, expanding understanding of magnetization interactions.

Findings

Spin currents can be generated optically without microwaves.

Resonant precession frequencies enhance coupling efficiency.

Coupled modes exhibit distinct decay rates.

Abstract

We demonstrate spin pumping, i.e. the generation of a pure spin current by precessing magnetization, without application of microwave radiation commonly used in spin pumping experiments. We use femtosecond laser pulses to simultaneously launch the magnetization precession in each of two ferromagnetic layers of a Galfenol-based spin valve and monitor the temporal evolution of the magnetizations. The spin currents generated by the precession cause a dynamic coupling of the two layers. This coupling has dissipative character and is especially efficient when the precession frequencies in the two layers are in resonance, where coupled modes with strongly different decay rates are formed.