Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 19: POSTER Ia

MA 19.41: Poster

Dienstag, 17. März 2015, 09:30–13:00, Poster A

Exchange bias in perpendicularly magnetized AFM/FM double layers — •Orestis Manos, Manuel Glas, Jan Schmalhorst, and Günter Reiss — Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Germany.

Recently, the combination of exchange bias (EB) systems and perpendicularly magnetized electrodes in magnetic tunnel junctions (pMTJs) has attracted considerable scientific interest. Exchange bias refers to the shift of the magnetic hysteresis loop away from zero field, due to the exchange interaction between a ferromagnet (FM) and an antiferromagnet (AFM) (e.g., FeMn) across their common interface, which is usually accompanied by an increase in coercivity. The EB in in-plane magnetized systems is based on the alignment of the crystal plane parallel to the sample surface. It is already realized that the crystallographic growth of the AFM material affects critically the existence of exchange bias. In principle, the first aim concerns the change of the growth direction of FeMn (111) perpendicular to the sample plane. Therefore, we have fabricated perpendicularly magnetized stacks consisting of A/Fe-Mn/Co-Fe-B/MgO with A = Pt, Ru, and Ta [1]. Afterwards, the samples were ex-situ post-annealed at several temperatures and their crystallographic properties were investigated by X-ray diffraction (XRD) spectroscopy. A [111] growth direction was obtained for all seed layer. Laue oscillations on the (111) FeMn reflex suggest a highly ordered thin film.The samples with Pt seed layer showed an exchange bias field of 50 Oe.
[1] F. Garcia et al., J. Appl. Phys. 91, 6905 (2002)