Ultrafast element- and depth-resolved magnetization dynamics probed by transverse magneto-optical Kerr effect spectroscopy in the soft x-ray range

TL;DR

This paper introduces a novel soft x-ray spectroscopy technique to analyze element-specific, depth-resolved ultrafast magnetization dynamics in nanostructured magnetic materials, revealing insights into spin behavior at buried interfaces.

Contribution

It presents a new time- and angle-resolved magneto-optical Kerr effect spectroscopy method that enables element-specific, depth-resolved analysis of femtosecond laser-induced spin dynamics.

Findings

Depth-dependent magnetization dynamics in GdFe films elucidated.

Disentanglement of electron transport and heat diffusion effects.

Quantitative insights into spin behavior at buried interfaces.

Abstract

We report on time- and angle-resolved transverse magneto-optical Kerr effect spectroscopy in the soft x-ray range that, by analysis via polarization-dependent magnetic scattering simulations, allows us to determine the spatio-temporal and element-specific evolution of femtosecond laser-induced spin dynamics in nanostructured magnetic materials. In a ferrimagnetic GdFe thin film system, we correlate a reshaping spectrum of the magneto-optical Kerr signal to depth-dependent magnetization dynamics and disentangle contributions due to non-equilibrium electron transport and nanoscale heat diffusion on their intrinsic time scales. Our work provides a quantitative insight into light-driven spin dynamics occurring at buried interfaces of complex magnetic heterostructures, which can be tailored and functionalized for future opto-spintronic devices.