Harnessing magnetic anisotropy for nonlinear magnetization precession and spin waves

TL;DR

This paper explores how magnetic anisotropy influences nonlinear magnetization dynamics and spin wave behavior in iron films, demonstrating effects like harmonic generation and rectification driven by external magnetic fields.

Contribution

It reveals the role of energy potential asymmetry in nonlinear effects and links energy profile geometry to nonlinear responses, aiding magnonic device design.

Findings

Demonstrated anharmonic magnetization precession and higher harmonics

Linked energy potential asymmetry to nonlinear effects

Showed external magnetic field near hard axis induces nonlinearity

Abstract

The nonlinearity of magnetization precession and spin waves is a cornerstone of contemporary magnonics. We investigate nonlinear magnetization dynamics in a thin epitaxial iron film driven by femtosecond laser pulses in regimes of homogeneous precession and propagating magnetostatic spin wave packets. The magnetization precession anharmonicity, the generation of higher-order harmonics, and the dynamical rectification are experimentally demonstrated. The numerical solution of the non-linearized Landau-Lifshitz-Gilbert equation reveals that these effects stem from the asymmetry in the energy potential. This asymmetry is readily achievable when an external magnetic field with a strength comparable to the magnetic anisotropy field is applied close to the hard axis. This work establishes a connection between the geometry of the energy profile and nonlinear responses, paving the way for designing magnonic devices with controlled harmonic generation and nonlinear spin wave interaction.