Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 18: Spindependent Transport II
MA 18.7: Vortrag
Mittwoch, 28. März 2007, 16:45–17:00, H22
Point-contact Andreev spectroscopy on Ni2MnIn and Ni80Fe20 — •Lars Bocklage, Jan M. Scholtyssek, Ulrich Merkt, and Guido Meier — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg
We measure the spin polarization of permalloy and the Heusler alloy Ni2MnIn using point-contact Andreev reflection spectroscopy [1]. Permalloy and Ni2MnIn are interesting materials for spintronic devices. Permalloy yields a highly spin-polarized current within a few nanometers. For the L21 structure of Ni2MnIn full spin polarization is predicted at the interface to InAs [2]. Permalloy films are deposited on Si and on Si covered with a thin highly conductive Au layer. The latter almost eliminates the series resistance of the ferromagnetic film and thus facilitates the interpretation of the differential conductance curves. For permalloy we determine a spin polarization of 35%. Ni2MnIn is evaporated on Si and on in situ cleaved (110) surfaces of InAs. The spin polarization of Ni2MnIn crucially depends on its crystal structure. For our present Heusler films we determine a spin polarization of about 30%. The low value is presumably caused by the presence of the undesired B2 structure.
[1] L. Bocklage et al., J. Appl. Phys., accepted (2007);
J. M. Scholtyssek et al., J. Magn. Magn. Mat., accepted (2006).
[2] K. A. Kilian and R. H. Victora, IEEE Trans. Mag. 37, 1976 (2001).