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@PHDTHESIS{Zhou:139787,
author = {Zhou, Xianzhong},
title = {{T}emperature-{I}nduced {M}etamagnetic {T}ransition and
{D}omain {S}tructures of {S}ingle-{C}rystalline {F}e{R}h
{T}hin {F}ilms on {M}g{O}(100)},
volume = {76},
school = {Universität Köln},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2013-05759},
isbn = {978-3-89336-919-5},
series = {Schriften des Forschungszentrums Jülich. Reihe
Schlüsseltechnologien / Key Technologies},
pages = {XI, 104 S.},
year = {2013},
note = {Universität Köln, Diss., 2013},
abstract = {Exchange systems of FeRh with a hard magnetic layer are a
promising approach for heat-assisted magnetic recording that
can largely increase the storage density of hard disk
drives. The FeRh alloy is known to undergo a
temperature-induced metamagnetic transition from
antiferromagnetic (AFM) to ferromagnetic (FM) just above the
room temperature. But the AFM and FM phases coexist across
the transition in single-crystalline FeRh thin lms with thin
capping layers (e.g. Au, Al, or MgO). In order to
investigate the intrinsic surface magnetic properties,
single-crystalline FeRh films without capping layer are
prepared by two kinds of experimental procedures. For the
ex-situ sample preparation procedure, two 40nm thick,
single-crystalline FeRh films are prepared on MgO(100) by
separate layer deposition of Fe and Rh. X-ray photoemission
spectroscopy (XPS) immediately after the deposition shows
that one sample is Rh-rich and the other Fe-rich. The
samples are exposed to air and transferred to a second
ultra-high vacuum (UHV) system to perform the magnetic
characterization. This transfer results in a contamination
by C and O. After surface cleaning by high-temperature
annealing the Rh-rich sample is still slightly contaminated
with C, while the Fe-rich surface is oxidized.
Magneto-optical Kerr effect (MOKE) measurements reveal that
only the Rh-rich sample shows the metamagnetic transition
below room temperature. The Fe-rich sample is FM at 193 and
293 K. Scanning electron microscopy with polarization
analysis (SEMPA) reveals that the Rh-rich surface is FM at
all temperatures between 160 and 450K although the bulk is
AFM below room temperature. For the in-situ sample
preparation procedure, a 10nm single-crystalline FeRh film
is prepared on MgO(100) again by separate layer deposition
of Fe and Rh but now in the same UHV system as all
characterizations. Thus, the intrinsic properties of the
single-crystalline FeRh film are investigated without
exposure to air and additional cleaning steps. The in-situ
prepared FeRh lm also exhibits the metamagnetic phase
transition below room temperature as indicated by MOKE. The
temperature dependent domain structure obtained by SEMPA
reveals that FM domains exist at the surface while the bulk
is AFM. In contrast to the ex-situ prepared sample the
domain size changes drastically at the transition
temperature. This is related to a spin reorientation
transition from out-of-plane to in-plane between 350 to 400
K. The results show that the previously observed coexistence
of the FM state at the surface and the AFM phase in the bulk
is not due to an artifact of capping layers or surface
contamination. This coexistence is shown in this work to be
an intrinsic property of (100) surfaces of
single-crystalline FeRh thin films on MgO(100).},
keywords = {Dissertation (GND)},
cin = {PGI-6},
cid = {I:(DE-Juel1)PGI-6-20110106},
pnm = {422 - Spin-based and quantum information (POF2-422)},
pid = {G:(DE-HGF)POF2-422},
typ = {PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/139787},
}