Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 18: Magnetic Coupling Phenomena
MA 18.1: Vortrag
Dienstag, 1. April 2014, 14:00–14:15, HSZ 403
Exchange Bias driven by Dzyaloshinskii-Moriya interactions — •Rocio Yanes1, Jerome Jackson2, Laszlo Udvardi3, Laszlo Szunyogh3, and Ulrich Nowak1 — 1Universität Konstanz, Konstanz, Germany — 2Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — 3Budapest University of Technology and Economics, Budapest, Hungary
The exchange bias (EB) effect is an effective unidirectional anisotropy in a heterogeneous magnetic system that leads to a shift in the hysteresis loop. It is widely accepted that the EB is related to the nature of coupling between a ferromagnet (FM) and an antiferromagnet (AFM).
We studied the origin of EB in a metallic IrMn3/Co(111) bilayer, using multiscale modeling, from ab-initio to localized spin model simulations. IrMn3 is a frustrated antiferromagnet which presents a strong second order effective anisotropy and a high Néel temperature. It exhibits a triangular magnetic ground state within the (111) plane. When this alloy is capped by a Co layer, sizable Dzyaloshinskii-Moriya (DM) interactions arise owing to the breaking of symmetry at the interface [1]. DM interactions between the Co and Mn atoms result in an effective DM field on the Co spins, oriented normal to the interface.
A detailed analysis of the hysteresis loops reveals that the DM interactions across the IrMn3/Co interface are the main source of perpendicular EB in this system [2]. This work was partially supported by the FP7-NMP-2013-EU-Japan project HARFIR.
[1] L. Szunyogh et. al., Phys. Rev. B 83, 024401 (2011).
[2] R. Yanes et. al., Phys. Rev. Lett, 111, 217202 (2013).