Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 23: Magnetic Thin Films II

MA 23.1: Talk

Wednesday, March 25, 2009, 14:45–15:00, HSZ 04

Effect of a Cr overlayer on the switching field of epitaxial FeCo contacts on GaAs(001) — •Bernhard Endres, Julien Vigroux, and Günther Bayreuther — University Regensburg Germany

Many experiments on spin-dependent transport require separate switching fields, H_S, for two ferromagnetic contacts for alternating between a parallel and an antiparallel magnetic configuration. For the case of two identical contact materials, magnetic pinning of one of the contacts by a suitable overlayer seems an appropriate solution. In this study Cr was used as a magnetic pinning material for MBE-grown Fe₃₄Co₆₆ contacts. The influence of a Cr overlayer grown by sputter-deposition was investigated for different Fe₃₄Co₆₆ thicknesses and at various temperatures. It is shown that a Cr overlayer leads to a more than five-fold increase of the easy axis switching field of Fe₃₄Co₆₆ films for all temperatures from 10 K to room temperature.

By the use of two shadow masks, two Fe₃₄Co₆₆ contacts on GaAs(001) could be realized, one pinned by a Cr layer on top and one without Cr with a 10 µ m wide gap in between. Since a spin decay length up to 30 µ m for an injected spin polarized current into GaAs was found in a previous experiment [1], the present layer structure should allow for all-electric detection of spin injection in GaAs. Finally, the influence of a Cr overlayer on domain nucleation and wall propagation is discussed in comparison to numerical simulations of the spin configuration at the FeCo-Cr interface.

[1] P. Kotissek et al., Nature Physics 3, 872, (2007)