Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 33: Magnetic Coupling Phenomena/ Exchange Bias

MA 33.6: Talk

Wednesday, March 28, 2012, 16:30–16:45, EB 202

Exchange Bias in IrMn₃/Co bilayers — •Rocio Yanes¹, Laszlo Szunyogh², and Ulrich Nowak¹ — ¹Universität Konstanz, Konstanz, Germany — ²Budapest University of Technology and Economics, Budapest, Hungary

The exchange bias (EB) effect is a unidirectional anisotropy of a magnetic system, which is characterized by a shift in the hysteresis loop, called exchange bias field H_E. The EB is related to the coupling between a ferromagnet (FM) and an antiferromagnet (AFM) or ferrimagnet (FI), and its stiffness depends on the exchange coupling through the interface.

We studied the magnetic properties of a bilayer of IrMn₃/Co using a multiscale modeling, from ab-initio to spin model simulations. The IrMn₃ is an AFM which exhibits a T1 magnetic ground state within a [111] magnetic easy plane [1]. When the IrMn₃ is capped by a Co layer, a measurable Dzyaloshinskii-Moriya (DM) interaction arises owing to the breaking of symmetry at the interface [2].

Numerical calculations of the hysteresis loops of IrMn₃/Co were carried out for different values of the thickness of the Co capping and the different contributions to the exchange interaction. The results show that IrMn₃/Co displays a strong EB effect and its origin is the DM interaction.

[1] L. Szunyogh, et.al., Phys. Rev. B, 79,020403(R) (2009)

[2] L. Szunyogh, et.al., Phys. Rev. B, 83,024401 (2011)