Ultrafast Spindynamics in Ferromagnetic Thin Films Alexander Weber

116 Pages·2012·19.66 MB·English

Ultrafast magnetization dynamics describe the physics of a magnetic
system on the perturbation by a strong laser pulse. This pulse excites
the electrons close to the Fermi energy. It is followed by a thermaliza-
tion due to a variety of scattering processes. The plenitude of these
processes is of fundamental interest for solid states physics, but is
not yet understood properly. In the field of ultrafast magnetization
dynamics most progress was achieved by all optical measurements.
However, the interpretation of all optical experiments is still under de-
bate. In order to gain direct insight into the time evolution of the spin 8
2
polarization a time and spin-resolved pump-probe experiment is ap-
d
plied. This allows one to measure the quenching of the spin polariza- n
tion without any optical contributions. In our experiment the spin po- a
B
larization of the photoexcited electrons of in situ prepared thin Fe and
-
Co films is measured directly with a Mott-detector. The overall signal k
shape matches the one of the all optical measurements. Thus, with si
y
the help of our measurements it could thus be shown, that the all h
optical techniques indeed contain a contribution of magnetic origin. P

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9 783868450897
Alexander Weber
Ultrafast Spindynamics in
Ferromagnetic Thin Films
Ultrafast Spindynamics in Ferromagnetic Thin Films
Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.)
der F akultät für Physik der Universität Regensburg
vorgelegt von
Alexander Weber
aus Regensburg
2010
Die Arbeit wurde von Prof. Dr. C. H. Back angeleitet.
Das Promotionsgesuch wurde am 30.06.2010 eingereicht.
Prüfungsausschuss: Vorsitzender: Prof. Dr. V. Braun
1. Gutachter: Prof. Dr. C. H. Back
2. Gutachter: Prof. Dr. J. Repp
weiterer Prüfer: Prof. Dr. C. Strunk
Dissertationsreihe der Fakultät für Physik der Universität Regensburg,
Band 28
Herausgegeben vom Präsidium des Alumnivereins der Physikalischen Fakultät:
Klaus Richter, Andreas Schäfer, Werner Wegscheider, Dieter Weiss
Alexander Weber
Ultrafast Spindynamics in
Ferromagnetic Thin Films
Bibliografische Informationen der Deutschen Bibliothek.
Die Deutsche Bibliothek verzeichnet diese Publikation
in der Deutschen Nationalbibliografie. Detailierte bibliografische Daten
sind im Internet über http://dnb.ddb.de abrufbar.
1. Auflage 2012
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Konzeption: Thomas Geiger
Umschlagentwurf: Franz Stadler, Designcooperative Nittenau eG
Layout: Alexander We ber
Druck: Docupoint, Magdeburg
ISBN: 978-3-86845-089-7
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4.1 First Measurements....–.................................................27
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4.2 Problem of Angular Momentum Conservation ........................... 29
4.3 Relation between Short and Long Time Processes ....................... 32
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