Electronic processes occurring during ultrafast demagnetization of cobalt triggered by X-ray photons tuned to Co L$_3$ resonance

TL;DR

This paper presents a theoretical analysis of electronic processes during ultrafast X-ray-induced demagnetization in cobalt, revealing that electronic mechanisms dominate until structural damage occurs, aligning well with experimental observations.

Contribution

It provides a detailed theoretical explanation of electronic processes in X-ray induced demagnetization of cobalt, emphasizing their predominant role and aligning with experimental data.

Findings

Electronic processes are key in demagnetization below damage threshold.

Theoretical results match experimental data without invoking stimulated elastic forward scattering.

Electronic mechanisms explain ultrafast demagnetization phenomena in cobalt.

Abstract

Magnetization dynamics triggered with ultrashort laser pulses has been attracting significant attention, with strong focus on the dynamics excited by VIS/NIR pulses. Only recently, strong magnetic response in solid materials induced by intense X-ray pulses from free-electron lasers (FELs) has been observed. The exact mechanisms that trigger the X-ray induced demagnetization are not yet fully understood. They are subject of on-going experimental and theoretical investigations. Here, we present a theoretical analysis of electronic processes occurring during demagnetization of Co multilayer system irradiated by X-ray pulses tuned to L$_3$-absorption edge of cobalt. We show that, similarly as in the case of X-ray induced demagnetization at M-edge of Co, electronic processes play a predominant role in the demagnetization until the pulse fluence does not exceed the structural damage threshold. The impact of electronic processes can reasonably well explain the available experimental data, without a need to introduce the mechanism of stimulated elastic forward scattering.