Surface Acoustic Wave-Driven Ferromagnetic Resonance in Nickel Thin Films: Theory and Experiment

TL;DR

This paper combines experimental and theoretical approaches to study how surface acoustic waves induce ferromagnetic resonance in nickel thin films, providing insights into magnetization dynamics and acoustic wave interactions.

Contribution

It introduces a comprehensive modeling framework for surface acoustic wave-driven ferromagnetic resonance, integrating magnetization dynamics with elastic wave behavior, validated by experimental data.

Findings

Quantitative agreement between model predictions and experimental measurements.

Consistent parameters describe power absorption and phase shift across different configurations.

Analytical solutions for acoustic wave phase shift and attenuation obtained.

Abstract

We present an extensive experimental and theoretical study of surface acoustic wave-driven ferromagnetic resonance. In a first modeling approach based on the Landau-Lifshitz-Gilbert equation, we derive expressions for the magnetization dynamics upon magnetoelastic driving that are used to calculate the absorbed microwave power upon magnetic resonance as well as the spin current density generated by the precessing magnetization in the vicinity of a ferromagnet/normal metal interface. In a second modeling approach, we deal with the backaction of the magnetization dynamics on the elastic wave by solving the elastic wave equation and the Landau-Lifshitz-Gilbert equation selfconsistently, obtaining analytical solutions for the acoustic wave phase shift and attenuation. We compare both modeling approaches with the complex forward transmission of a LiNbO$_3$/Ni surface acoustic wave hybrid device recorded experimentally as a function of the external magnetic field orientation and magnitude, rotating the field within three different planes and employing three different surface acoustic wave frequencies. We find quantitative agreement of the experimentally observed power absorption and surface acoustic wave phase shift with our modeling predictions using one set of parameters for all field configurations and frequencies.