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@PHDTHESIS{Tillmanns:52128,
author = {Tillmanns, Andrea},
othercontributors = {Güntherodt, Gernot},
title = {{M}agnetisierungsumkehr und -dynamik in
{E}xchange-{B}ias-{S}ystemen},
address = {Aachen},
publisher = {Publikationsserver der RWTH Aachen University},
reportid = {RWTH-CONV-114369},
pages = {II, 171 S. : graph. Darst.},
year = {2005},
note = {Prüfungsjahr: 2005. - Publikationsjahr: 2006; Aachen,
Techn. Hochsch., Diss., 2005},
abstract = {The present thesis describes magneto-optical analyses of
exchange bias thin film systems. Exchange bias (EB) is a
unidirectional anisotropy originating from coupling of a
ferromagnetic with an antiferromagnetic layer. The
magneto-optical Kerr effect (MOKE) allows for detection of
the longitudinal (parallel to an external field) as well as
the transverse magnetization component (perpendicular to an
external field). As shown in this thesis, both measurement
can be performed within a single optical setup.
Additionally, a magneto-optical pump-probe-setup provides
the possibility of studying time-resolved magnetization
reversal (on timescales of ps). Here, asymmetric
magnetization reversal processes are of special interest.
They have only been observed in EB systems and are generally
attributed to different reversal mechanisms – coherent
rotation on one side of the hysteresis loop, domain wall
nucleation and propagation on the other side. The observed
signals can be reproduced with a simulation that deals with
the coherent rotation of a single magnetic moment. The
shapes of the measured hysteresis loops allow for
determination of the angle dependent energy density function
of the studied samples. The exchange bias turns out to be
the cause for the observed asymmetries. In the second part
of this thesis, time-resolved measurements of exchange bias
systems show a precession of the magnetization around the
effective field after the pump pulse has changed the
anisotropies of the sample by means of a local heating. The
precession occurs on a timescale of some ten picoseconds.
Analysis of the precession frequency depending on the sample
orientation again allows the exact determination of the
energy density function as well as the anisotropy constants
of the particular sample. Finally a method is presented
which permits seperation of the longitudinal, transverse and
polar (perpendicular to the sample surface) magnetization
components. Thus the three-dimensional trajectories
describing the precessing magnetic moments can be imaged. In
this manner, the time-resolved motions can be displayed in
addition to the static ones.},
cin = {100000},
ddc = {530},
cid = {$I:(DE-82)100000_20140620$},
typ = {PUB:(DE-HGF)11},
urn = {urn:nbn:de:hbz:82-opus-13522},
url = {https://publications.rwth-aachen.de/record/52128},
}
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