A microscopic model for ultrafast remagnetization dynamics

TL;DR

This paper introduces a microscopic model combining first principles calculations and atomistic spin dynamics to simulate ultrafast remagnetization in Fe and Co, revealing complex temporal magnetic behaviors across femtoseconds to picoseconds.

Contribution

It presents a novel integrated approach using density functional theory, Landau-Lifshitz-Gilbert dynamics, and a three temperature model to study ultrafast magnetic dynamics.

Findings

Complex temporal evolution of atomic moments and magnetization.

Non-monotonic macro spin behavior due to electron, spin, and lattice interactions.

Demonstrates the interplay of subsystems affects ultrafast remagnetization.

Abstract

In this letter, we provide a microscopic model for the ultrafast remagnetization of atomic moments already quenched above Stoner-Curie temperature by a strong laser fluence. Combining first principles density functional theory, atomistic spin dynamics utilizing the Landau-Lifshitz-Gilbert equation and a three temperature model, we show the temporal evolution of atomic moments as well as the macroscopic magnetization of bcc Fe and hcp Co covering a broad time scale, ranging from femtoseconds to picoseconds. Our simulations show a variety of complex temporal behavior of the magnetic properties resulting from an interplay between electron, spin and lattice subsystems, which causes an intricate time evolution of the atomic moment, where longitudinal and transversal fluctuations result in a macro spin moment that evolves non-monotonically.