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@PHDTHESIS{Pltzing:819167,
author = {Plötzing, Moritz Alexander},
title = {{L}aser-{I}nduced {U}ltrafast {E}lectron- and
{S}pin-{D}ynamics in the {E}lectronic {B}and {S}tructure of
{C}o(001)},
volume = {131},
school = {Universität Duisburg},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2016-04878},
isbn = {978-3-95806-168-2},
series = {Schriften des Forschungszentrums Jülich. Reihe
Schlüsseltechnologien / Key Technologies},
pages = {II, 109, XXXIV S.},
year = {2016},
note = {Universität Duisburg, Diss., 2016},
abstract = {In the last two decades, ultrafast magnetization dynamics
has been the subject of a large number of experimental and
theoretical investigations, however, without establishing a
consistent picture up to now. The objective of the work
presented in this thesis is to provide a new and profound
perspective on the underlying mechanisms by a direct
observation of the spin-dynamics in the electronic band
structure of 3$\textit{d}$ ferromagnets using femtosecond
time- and spin-resolved photoelectron spectroscopy of the
full energy range of the valence bands. For this purpose, a
novel experimental setup has been developed and commissioned
that combines a modern, highly effcient spin detector with a
state-of-the-art, table-top light source creating ultrashort
extreme ultraviolet (XUV) pulses by laser-based high-order
harmonic generation (HHG). The light source can be used in
two operation modes, which provide XUV radiation with
different wavelengths and photon fluxes. Static
spin-resolved photoemission spectra of Co(001) films have
been measured in both operation modes to find the optimum
conditions for time-resolved experiments. Moreover, vacuum
space-charge (VSC) effects within the dense electron clouds
emitted by the femtosecond XUV pulses as well as the Coulomb
interaction between electron clouds generated by XUV probe-
and near-infrared (NIR) pump-pulses in a pump-probe
experiment have been investigated in detail. The findings
are used to determine and later minimize the influence of
VSC on photoemission results. The NIR pump-pulses have been
employed in time-resolved measurements to trigger ultrafast
demagnetization in Co samples. Using the capabilities of the
new experiment, we monitored the time evolution of the
electron-dynamics by measuring spin-resolved spectra over a
broad energy range fully covering the valence bands. To our
knowledge, such measurements have been performed for the
first time. The experiments lead to novel insights into the
evolution of the spin system during an ultrafast
demagnetization process, in particular by showing evidence
of spin-mixing instead of a quenching of the exchange
splitting as suggested by the Stoner-model.},
cin = {PGI-6},
cid = {I:(DE-Juel1)PGI-6-20110106},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/819167},
}