Ultra-high frequency magnetic resonance through strain-spin coupling in perpendicular magnetic multi-layers

TL;DR

This study demonstrates ultra-high frequency magnetic resonance up to 60 GHz in perpendicular magnetic multilayers driven by strain-spin coupling, revealing a new pathway for high-frequency magnetic control using acoustic strain waves.

Contribution

It provides the first experimental observation of strain-induced magnetic resonance at ultra-high frequencies in perpendicular magnetic multilayers and introduces a theoretical model explaining the energy transfer mechanism.

Findings

Detection of 10 ps response acoustic strain waves in multilayers

Observation of magnetic resonance up to 60 GHz

Theoretical model explaining strain-spin energy transfer

Abstract

The interaction between strain and spin has received intensive attention in the scientific community due to its abundant physical phenomena and huge technological impact. Until now, there is no experimental report on ultra-high frequency magnetic resonance through the strain-spin coupling for any technologically relevant perpendicular magnetic material. Here we report the experimental detection of the acoustic strain waves that have a response time on the order of 10 picoseconds in perpendicular magnetic [Co/Pd]n multilayers via a femtosecond laser pulse excitation. Through direct measurements of acoustic strain waves, we observe an ultra-high frequency magnetic resonance up to 60 GHz in [Co/Pd]n multilayers. We further report a theoretical model of the strain-spin interaction. Our model reveals that the energy could be transferred efficiently from the strain to the spins and well explains the existence of a steady resonance state through exciting the spin system. The physical origins of the resonance between strain waves and magnetic precession and the requested conditions for obtaining magnetic resonance within thin magnetic films have also been discussed after thorough analysis. These combined results point out a potential pathway to enable an extremely high frequency (EHF) magnetic resonance through the strain-spin coupling.