Spectroscopic probe of ultrafast magnetization dynamics in the extreme ultraviolet spectral range

TL;DR

This paper introduces a novel XUV spectroscopic geometry that enables the observation of ultrafast magnetization dynamics in magnetic systems with out-of-plane magnetization on opaque substrates, combining magneto-optical Kerr effect with reflectance dependence near Brewster angle.

Contribution

A new geometry for XUV spectroscopy that allows ultrafast magnetization studies without additional polarizers, applicable to opaque substrates with out-of-plane magnetization.

Findings

Validated the technique with simulations and experiments.

Demonstrated energy and polarization dependence of the ultrafast dynamics.

Showed the method's effectiveness in real magnetic systems.

Abstract

The development of spectroscopic techniques in the extreme ultraviolet (XUV) spectral range has significantly advanced the understanding of ultrafast interactions in magnetic systems triggered by optical excitation. In this work, we introduce a previously missing geometry that facilitates the observation of the ultrafast magnetization dynamics of magnetic systems with an out-of-plane magnetization grown on XUV opaque substrates. This approach to probing ultrafast magnetization dynamics combines the magneto-optical Kerr effect with the strong dependence of a sample's reflectance near its Brewster angle. It therefore works with linearly polarized light and does not require any additional polarizing optics. We provide a comprehensive analysis of the technique by presenting both simulations and experimental data as a function of the energy and the polarization of the XUV probe radiation as well as of the delay time after optical excitation.