  The ultrafast and element-specific response of magnetic systems containing
ferromagnetic 3d transition metals and 4d/5d heavy metals is of interest both
from a fundamental as well as an applied research perspective. However, to date
no consensus about the main microscopic processes describing the interplay
between intrinsic 3d and induced 4d/5d magnetic moments upon femtosecond laser
excitation exist. In this work, we study the ultrafast response of CoFeB/Pt
bilayers by probing element-specific, core-to-valence band transitions in the
extreme ultraviolet spectral range using high harmonic radiation. We show that
the combination of magnetic scattering simulations and analysis of the energy-
and time-dependent magnetic asymmetries allows to accurately disentangle the
element-specific response in spite of overlapping Co and Fe M$_{2,3}$ as well
as Pt O$_{2,3}$ and N$_7$ resonances. We find a considerably smaller
demagnetization time constant as well as much larger demagnetization amplitudes
of the induced moment of Pt compared to the intrinsic moment of CoFeB. Our
results are in agreement with enhanced spin-flip probabilities due to the high
spin-orbit coupling localized at the heavy metal Pt, as well as with the
recently formulated hypothesis that a laser generated, incoherent magnon
population within the ferromagnetic film leads to an overproportional reduction
of the induced magnetic moment of Pt.
