Nonlinear Spin Dynamics in Ferromagnets with Electron-Nuclear Coupling

TL;DR

This paper investigates nonlinear spin dynamics in ferromagnets with electron-nuclear interactions and resonator feedback, revealing mechanisms for ultrafast coherent relaxation useful for probing magnetic material properties.

Contribution

It provides a comprehensive analysis of nonlinear spin motion considering nonequilibrium states, hyperfine coupling, and resonator feedback, highlighting conditions for ultrafast coherent relaxation.

Findings

Coherent spin motion can develop due to combined nonlinear effects.

Ultrafast relaxation mechanisms are identified for strongly nonequilibrium states.

Resonator feedback significantly influences spin dynamics and relaxation times.

Abstract

Nonlinear spin motion in ferromagnets is considered with nonlinearity due to three factors: (i) the sample is prepared in a strongly nonequilibrium state, so that evolution equations cannot be linearized as would be admissible for spin motion not too far from equilibrium, (ii) the system considered consists of interacting electron and nuclear spins coupled with each other via hyperfine forces, and (iii) the sample is inserted into a coil of a resonant electric circuit producing a resonator feedback field. Due to these nonlinearities, coherent motion of spins can develop, resulting in their ultrafast relaxation. A complete analysis of mechanisms triggering such a coherent motion is presented. This type of ultrafast coherent relaxation can be used for studying intrinsic properties of magnetic materials.