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@PHDTHESIS{Riepp:470997,
author = {Riepp, Matthias},
othercontributors = {Gruebel, Gerhard},
title = {{M}ulti-{S}cale {S}tudy of {A}ll-{O}ptically {I}nduced
{M}agnetization {D}ynamics in {C}o/{P}t {M}ultilayers
utilizing {TR}-m{SAXS} at {FEL} {S}ources},
school = {Universität Hamburg},
type = {Dissertation},
publisher = {Verlag Deutsches Elektronen-Synchrotron DESY},
reportid = {PUBDB-2021-04314, DESY-THESIS-2021-018},
series = {DESY-THESIS},
pages = {210},
year = {2021},
note = {Dissertation, Universität Hamburg, 2021},
abstract = {This thesis deals with the impact of ultrashort
near-infrared~(nIR) and extreme ultraviolet~(XUV) laser
pulses on the magnetic multi-domain states of particularly
thin Co/Pt multilayers. The laser induced magnetization
dynamics are investigated with femtosecond time and
nanometer spatial resolution utilizing time-resolved
magnetic small-angle X-ray scattering~(TR-mSAXS) at the
free-electron lasers~(FEL) FLASH in Hamburg and
FERMI@Elettra in Trieste.One part of the thesis deals with
ultrafast demagnetization in three different
Co/Pt-multilayer samples with total film thicknesses in the
range of the attenuation length of nIR radiation in Co and
Pt. For excitation of the magnetic states, nIR-laser pulses
of different fluence, pulse duration and polarization are
used, addressing important aspects of ultrafast
demagnetization in such optically thin Co/Pt multilayers,
for the first time, by resonant magnetic scattering. In
particular, a model that accounts for both the
low-temperature behavior of the remagnetization dynamics and
its drastic slowing down at high temperatures is proposed,
taking into account recent theoretical predictions. Within
this model, the remagnetization dynamics are described via
energy exchange between a strongly coupled electron-spin
system and the phonon system.Another part of the thesis
addresses the influence of nIR and XUV-laser~(FEL) pulses on
the lateral configuration of nanoscopic multi-domain states.
Different multi-domain states are generated in a selected
Co/Pt multilayer by using out-of-plane~(OOP) magnetic
fields. Aside from ultrafast demagnetization, that behaves
similar for the different multi-domain states, permanent
lateral domain modifications forming on longer time scales
are observed, that do depend on the underlying multi-domain
state. Moreover, the permanent modifications only occur if
nIR and XUV-laser pulses temporally overlap. Since the
action of the combined~(pump/probe) peak intensity alone
cannot explain the observed effects, it is concluded that
the permanent modifications also depend on the photon
energies of the laser pulses. In particular, the permanent
modifications in the close-to single-domain state point at
laser induced nucleation processes and thus a novel
all-optical switching~(AOS) like mechanism that is based on
the interplay of two different laser excitations.},
cin = {FS-CXS},
cid = {I:(DE-H253)FS-CXS-20130727},
pnm = {632 - Materials – Quantum, Complex and Functional
Materials (POF4-632) / 6G2 - FLASH (DESY) (POF4-6G2) / 6G3 -
PETRA III (DESY) (POF4-6G3) / PHGS, VH-GS-500 - PIER
Helmholtz Graduate School $(2015_IFV-VH-GS-500)$},
pid = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G2 /
G:(DE-HGF)POF4-6G3 / $G:(DE-HGF)2015_IFV-VH-GS-500$},
experiment = {EXP:(DE-H253)F-BL3-20150101 / EXP:(DE-MLZ)External-20140101
/ EXP:(DE-H253)P-P04-20150101},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
doi = {10.3204/PUBDB-2021-04314},
url = {https://bib-pubdb1.desy.de/record/470997},
}