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@PHDTHESIS{Steffen:808753,
author = {Steffen, Alexandra},
title = {{S}elf-purifying {L}a$_{2/3}${S}r$_{1/3}${M}n{O}$_{3}$
epitaxial films: {O}bservation of surface precipitation of
{M}n$_{3}${O}$_{4}$ particles for excess {M}n ratios},
volume = {128},
school = {RWTH Aachen},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2016-02374},
isbn = {978-3-95806-162-0},
series = {Schriften des Forschungszentrums Jülich. Reihe
Schlüsseltechnologien / Key Technologies},
pages = {154 S.},
year = {2016},
note = {RWTH Aachen, Diss., 2016},
abstract = {20-25 nm thin films based La$_{2/3}$Sr$_{1/3}$MnO$_{3}$
(LSMO) are prepared via Oxide Molecular Beam Epitaxy setup
(MBE). Different ways of effusion cell shutter opening
intervals are used to produce samples in co-deposition and
shuttered mode. In-situ Reflection High-Energy Electron
Diffraction (RHEED) intensity measurements in dependence of
evaporation time are performed. The RHEED intensities
exhibit distinct oscillations, indicating a stacking of
layers with a stoichiometry controlled by the shutter
opening times, in particular of the La$_{2/3}$Sr$_{1/3}$O
vs. MnO content. Inside the thin LSMO films, vertical
stoichiometric constant and gradient structures are
produced. Low Energy Electron Diffraction (LEED) and X-Ray
Diffraction (XRD) exhibit the Bragg reflection sexpected for
epitaxial growth of the thin films. XRR analysis is in
agreement with the nominal layer thickness and composition.
To determine the magnetic layer thickness and to see whether
a magnetic gradient inside the structural gradient takes
place, Polarized Neutron Reflectometry (PNR) measurements
are performedand evaluated. The depth-dependent
magnetization behavior does not render the anticipated
sample structure. A combined refinement of XRR and PNR data
requires MnOx excess towards the surfaces in the model of
the scattering length density. Additional High-Resolution
Transmission Electron Microscopy (HRTEM) images reveal the
existence of pure homogeneous perovskite LSMO layers with
enclaved MnOx precipitates. Detailed SQUID measurements
indicate these particles to have a M$_{3}$O$_{4}$
stoichiometry. Due to the combination of different
experimental methods, the difference between the nominal and
the actual layer composition can be identified showing that
LSMO prefers to grow in pure La$_{2/3}$Sr$_{1/3}$MnO$_{3}$
perovskite phase on SrTiO$_{3}$. The observation of this
phase separation effect will be discussed.},
cin = {JCNS-2 / PGI-4 / JARA-FIT / JCNS (München) ; Jülich
Centre for Neutron Science JCNS (München) ; JCNS-FRM-II},
cid = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)PGI-4-20110106 /
$I:(DE-82)080009_20140620$ /
I:(DE-Juel1)JCNS-FRM-II-20110218},
pnm = {144 - Controlling Collective States (POF3-144) / 524 -
Controlling Collective States (POF3-524) / 6212 - Quantum
Condensed Matter: Magnetism, Superconductivity (POF3-621) /
6213 - Materials and Processes for Energy and Transport
Technologies (POF3-621) / 6G4 - Jülich Centre for Neutron
Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-144 / G:(DE-HGF)POF3-524 /
G:(DE-HGF)POF3-6212 / G:(DE-HGF)POF3-6213 /
G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)MARIA-20140101 / EXP:(DE-MLZ)TREFF-20140101},
typ = {PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/808753},
}