Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 91: [MA] Poster II

O 91.44: Poster

Friday, March 30, 2012, 11:00–14:00, Poster A

Observation of antiferromagnetic domains using magneto-optical microscopy. — •Anna Möhn, Ingolf Mönch, Denys Makarov, Rudolf Schäfer, Oliver G. Schmidt, and Ludwig Schultz — IFW Dresden, Institute for Metallic Materials Dresden, Germany

Two different exchange biased systems were studied. Both antiferromagnetic/ferromagnetic-bilayer systems contain Py as ferromagnetic material, but one with IrMn and the other one with CoO as antiferromagnetic layer. Through the different Néel-temperatures of the antiferromagntic materials the systems show the exchange bias effect under different temperature conditions. The exchange bias effect can be used to imprint a well-defined domain pattern into the antiferromagnetic layer. To observe those imprinted antiferromagnetic domains directly we will use the Voigt effect. This quadratic magneto-optical effect is a birefringence of linearly polarized light which we observe in reflection with a wide-field Kerr microscope. Using the Voigt effect on a ferromagnet, we can see domains which differ by 90^∘ in the axis of the magnetic moments independent of their net magnetization. The same effect is expected to be seen in an antiferromagnet if the antiferromagnetic domains are magnetized along orthogonal easy axes [1]. The required 90^∘ domains are firstly generated as a Landau pattern in the (structured) ferromagnetic film of our bilayer systems and then imprinted to the antiferromagnetic film by cooling below the blocking temperature.

[1] Peter Oppeneer, University Uppsalla, private communication