Ultrafast Entropy Production in Non-Equilibrium Magnets

TL;DR

This paper develops an ultrafast thermodynamics model for heat and entropy production in laser-driven magnetic materials, validated by experiments, with implications for spintronics and nanotech.

Contribution

It introduces a novel framework linking laser magnetic fields to entropy production and heat dissipation, incorporating inertial spin dynamics for the first time.

Findings

Validated theoretical predictions with experimental magnetization data.

Revealed the impact of inertial spin dynamics on heat generation.

Provided insights into controlling heat in magnetic systems.

Abstract

We present an ultrafast thermodynamics framework to model heat generation and entropy production in laser-driven ferromagnetic systems. By establishing a connection between the magnetic field strength of the laser pulse and magnetization dynamics we model time-dependent entropy production rates and deduce the associated heat dissipation in epitaxial and polycrystalline FeNi and CoFeB thin films. Our theoretical predictions are validated by comparison to experimental magnetization dynamics data, shedding light on thermodynamic processes on picosecond timescales. Crucially, we incorporate recently observed inertial spin dynamics, to describe their impact on heat generation in pump-probe experiments. As such, this formalism provides novel insights into controlling heat production in magnetic systems, and contributes to advancing the understanding of non-equilibrium thermodynamics in magnetic systems, with implications for future experimental protocols in spintronics and nanotechnology.