Femtosecond laser comb driven perpendicular standing spin waves

TL;DR

This paper demonstrates the generation of coherent perpendicular standing spin waves in permalloy films using femtosecond laser combs, showing their effectiveness across various film thicknesses and modes.

Contribution

It introduces a simple demagnetization model and shows femtosecond laser combs can excite multiple orders of standing spin waves in permalloy films.

Findings

Perpendicular standing spin waves up to third order observed.

Laser comb excitation effective across 40-100 nm film thickness.

Femtosecond combs serve as versatile contact-less spin wave sources.

Abstract

We study femtosecond laser comb driven sustained and coherent spin wave (SW) generation in permalloy (Py) films over a thickness range of $d =$ 40--100 nm. A simple rapid demagnetization model describes the dependence of the observed SW intensity on laser power for all film thicknesses. In the thicker films we observe laser comb excited perpendicular standing spin waves up to third order and to 18 multiples of the 1 GHz laser repetition rate. Our results demonstrate the versatility of femtosecond combs as contact-less SW point sources over a wide range of film thickness and type of SW modes.