Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.60: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Tuning the Exchange Bias in FeMn/Ni₈₁Fe₁₉ by nonmagnetic Cu defects in the FeMn layer — •J.O. Hauch, C. Papusoi, M. Fecioru, and G. Güntherodt — II. Physikalisches Institut, RWTH Aachen, 52056 Aachen

Previous theoretical [1] and experimental [2] work on CoO/Co antiferromagnetic/ferromagnetic (AFM/FM) bilayer systems revealed that increasing the nonmagnetic defect concentration at the Co site in the AFM layer leads to an enhancement of the exchange bias. In this study we present the dependence of the exchange bias in FeMn/Ni₈₁Fe₁₉ on nonmagnetic Cu dilution in the AFM layer. Experiments have been performed on Au(5nm)/(Fe₅₀Mn₅₀)_1−xCu_x(10nm)/Ni₈₁Fe₁₉(10nm)/Cu/SiO₂ layer systems. The exchange bias shows a maximum at around 10 % Cu defect concentration. These results can be explained as a consequence of a competition between two effects: The increase of the defect concentration leads to an increase of the number of uncompensated moments in the AFM enhancing the exchange bias. On the other hand, the distance of the nonmagnetic pinning sites is decreased by increasing Cu concentration inducing domain walls in the AFM layer. Thereby the thermal instability of the uncompensated moments is increased, thus decreasing the exchange bias. Monte Carlo simulations have peen performed to prove the above statement. [1] U. Nowak, K.D. Usadel, J. Keller, P. Miltenyi, B. Beschoten, and G. Güntherodt, Phys. Rev. B 66, 014430 (2002). [2] J. Keller, B. Beschoten, G. Güntherodt, U. Nowak, and K.D. Usadel, Phys. Rev. B 66, 014431 (2002).