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@ARTICLE{Yang:17482,
author = {Yang, S.-H. and Balke, B. and Papp, Ch. and Doering, S. and
Berges, U. and Plucinski, L. and Westphal, C. and Schneider,
C. M. and Parkin, S. S. P. and Fadley, C. S.},
title = {{D}etermination of layer-resolved composition,
magnetization, and electronic structure of an {F}e/{M}g{O}
tunnel junction by standing-wave core and valence
photoemission},
journal = {Physical review / B},
volume = {84},
number = {18},
issn = {1098-0121},
address = {College Park, Md.},
publisher = {APS},
reportid = {PreJuSER-17482},
pages = {184410},
year = {2011},
note = {B.B. and C.P. gratefully acknowledge the support through
the Feodor-Lynen fellowship of the Humboldt foundation. C.F.
also acknowledges support of the Helmholtz Association and
the Humboldt Foundation. Additionally, the experiments at
the Advanced Light Source and the participation of LBNL
Materials Sciences Division scientists were supported by
Department of Energy (DOE) Contract No. DE-AC02-05CH11231.},
abstract = {Spin-dependent tunneling across a highly textured MgO
insulating barrier has received much attention due to its
potential applications in various spintronic devices.
However, the interfacial magnetic and electronic structure
of a prototypical realization of this in Fe/MgO/Fe and the
effective band gap of the MgO layer are still under debate.
In order to resolve these issues, we have employed
standing-wave excited core and valence photoemission, as
well as core-level magnetic circular dichroism (MCD) in
photoemission, to study the Fe/MgO interface with
subnanometer depth resolution. For our synthetic procedure,
we show that the Fe/MgO interface is linearly intermixed in
composition over a length of similar to 8 angstrom (similar
to 4 monolayers) and that there is a magnetic dead layer
similar to 2-3 angstrom thick. The unambiguous extraction of
depth-resolved density of states (DOS) reveals that the
interfacial layer composition is mostly metallic and
nonmagnetic FeOx, with x congruent to 1, which accounts for
a smaller magnetoresistance compared to theoretical
predictions. The formation of the magnetic dead layer (FeO)
at the interface should also reduce the tunneling spin
polarization. The analysis of our data also shows a clear
valence band edge of ultrathin MgO layer at similar to 3.5
eV below the Fermi level (E-F) that is very close to that of
single crystal bulk MgO. An analysis that does not consider
the interdiffused region separately exhibits the valence
band edge for MgO layer similar to 1.3 eV below E-F, which
is significantly closer to the MgO barrier height estimated
from magnetotransport measurements and further suggests that
the Fe/MgO interdiffusion effectively reduces the MgO band
gap.},
keywords = {J (WoSType)},
cin = {PGI-6},
ddc = {530},
cid = {I:(DE-Juel1)PGI-6-20110106},
pnm = {Grundlagen für zukünftige Informationstechnologien},
pid = {G:(DE-Juel1)FUEK412},
shelfmark = {Physics, Condensed Matter},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000296911600004},
doi = {10.1103/PhysRevB.84.184410},
url = {https://juser.fz-juelich.de/record/17482},
}