Berlin 2008 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 25: SYM Thin Film Magnetic Materials: Microstructure, Reaction and Magnetic Coupling IV
MM 25.3: Vortrag
Mittwoch, 27. Februar 2008, 16:50–17:10, H 1058
Influencing the magnetic properties of NiMn/Co exchange bias system by pulsed laser irradiation — •Senthilnathan Mohanan1, Ulrich Herr1, Ralf Diebolder2, and Raimund Hibst2 — 1Insitut für Mikro- und Nanomaterialien, Universität Ulm, 89081 Ulm — 2Institut für Laseranwendungen in der Medizin und Meßtechnik, Universität Ulm, 89081 Ulm
NiMn with L10 ordered structure is a promising antiferromagnetic material that can be used to achieve exchange bias in giant magnetoresistive spin valve sensors. However, as-deposited NiMn exhibits the paramagnetic fcc phase and has to be annealed at an elevated temperature to obtain the L10 ordered antiferromagnetic fct phase. We present a study on the influence of ns pulsed laser irradiation using a Nd-YAG laser on the structural and magnetic properties of NiMn/Co exchange bias system [1]. X-ray diffraction spectra revealed that upon laser irradiation there is an improvement of the (111) texture of NiMn accompanied by grain growth, but no structural phase transformation. As-prepared and laser irradiated samples were subsequently annealed at different temperatures, and we observed increased exchange bias fields for the laser irradiated samples as compared to those of the as-prepared samples. Since no difference in the degree of ordering was found between as-prepared and laser irradiated samples after annealing, we attribute the observed increase in the exchange bias fields to the modified microstructure.
1. S. Mohanan, R. Diebolder, R. Hibst, and U. Herr, J. Appl. Phys. (accepted)