# Driving magnetization dynamics in an on-demand magnonic crystal by magneto-elastic interaction

## TL;DR

This paper demonstrates a method to dynamically control magnetization and spin-wave modes in a magnetic film using ultrafast laser interference, creating a reconfigurable magnonic crystal with tunable properties.

## Contribution

It introduces a spatial light interference technique to generate on-demand, configurable magnonic crystals and explores their magnetoelastic interactions and spin-wave control.

## Key findings

- Magnetoelastic coupling depends on magnetic field angle and strength.
- The interference pattern acts as a customizable magnonic crystal.
- Spin-wave modes can be spatially controlled and identified via simulations.

## Abstract

Using spatial light interference of ultrafast laser pulses, we generate a lateral modulation in the magnetization profile of an otherwise uniformly magnetized film, whose magnetic excitation spectrum is monitored via the coherent and resonant interaction with elastic waves. We find an unusual dependence of the magnetoelastic coupling as the externally applied magnetic field is angle- and field-tuned relative to the wave vector of the magnetization modulation, which can be explained by the emergence of spatially inhomogeneous spin-wave modes. In this regard, the spatial light interference methodology can be seen as a user-configurable, temporally windowed, on-demand magnonic crystal, potentially of arbitrary two-dimensional shape, which allows control and selectivity of the spatial distribution of spin waves. Calculations of spin waves using a variety of methods, demonstrated here using the plane-wave method and micromagnetic simulation, can identify the spatial distribution and associated energy scales of each excitation, which opens the door to a number of excitation methodologies beyond our chosen elastic wave excitation.