Experimental investigations of ultrafast magnetization dynamics increasingly employ resonant magnetic spectroscopy in the ultraviolet spectral range. Besides allowing to disentangle the element-specific transient response of functional magnetic systems, these techniques also promise to access attosecond to few-femtosecond dynamics of spin excitations. Here, we report on a systematic study of transient magnetic circular dichroism (MCD) on the transition metals Fe, Co and Ni as well as on a FeNi and GdFe alloy and reveal a delayed onset between the electronic and magnetic response. Supported by \textit{ab-initio} calculations, we attribute our observation to a transient energy shift of the absorption and MCD spectra at the corresponding elemental resonances due to non-equilibrium changes of electron occupations.
@article{arxiv.2005.02872,
title = {Distinct Ultrafast Electronic and Magnetic Response in M-edge Magnetic Circular Dichroism},
author = {Kelvin Yao and Felix Willems and Clemens von Korff Schmising and Ilie Radu and Christian Strueber and Daniel Schick and Dieter Engel and Arata Tsukamoto and J. K. Dewhurst and Sangeeta Sharma and Stefan Eisebitt},
journal= {arXiv preprint arXiv:2005.02872},
year = {2020}
}