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Magnetismus Poster: Do., 13:00–15:30 D-P225
Antiferromagnetic-Ferromagnetic Phase Transition in Fe50Pt50−xRhx Thin
Films
Jochen Fenske 1 , Dieter Lott 1 , Gary J. Mankey 2 , Prakesh Mani 2 , Frank
Klose 3 , Wolfgang Schmidt 4 , Andreas Schreyer 1
1 GKSS Research Centre, Institute for Material Science – 2 MINT Center, The University
of Alabama, Tuscaloosa, AL – 3 SNS, Oak Ridge Nat. Laboratory – 4 IN12, ILL,
Grenoble, France
In the last years perpendicular recording has been in the focus of scientific and technological
interest on the search for materials to overcome the limitations in the storage
density of conventional magnetic recording media. In order to reach the required
high writing magnetic fields a soft underlayer is needed to provide a closure field during
the writing process. An interesting candidate for such a magnetic underlayer is
Fe50Pt50−xRhx. For certain compositions an antiferromagnetic (AF) state exists at
lower temperatures which turns into a ferromagnetic (F) state at higher temperatures
[1]. Used as a magnetic underlayer it can provide a closure field when heated lowering
the write field. After the writing process the underlayer can be cooled again becoming
AF and hence helps to stabilize the recording media via exchange interactions. The
advantage of Fe50Pt50−xRhx compared to conventional underlayers like permalloy is
that even thinner system may be sufficient to provide the same closure field.
Neutron diffraction measurements were carried out to study the AF-F switching of thin
films of Fe50Pt50−xRhx in dependence of temperature and magnetic field. Three kinds
of AF ordering were observed, the (1/2 1/2 1/2), (0 0 1/2) and (1/2 1/2 3/2) depending
on temperature and magnetic field. Both magnetization and neutron diffraction
studies show the coexistence of an AF and F phase in a Fe50Pt40Rh10.
[1]P. A. Algarabel et al, Journal of Applied Physics, 79 (8) 4659(1996)