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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.67: Poster

Dienstag, 28. März 2006, 15:15–19:15, P1

Co moment reduction in the NiCoO/Co exchange bias system — •Sebastian Brück¹, Uwe Grüner¹, Myrsini Lafkioti¹, YunJun Tang², Eberhard Goering¹, and Ami E. Berkowitz² — ¹Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart — ²University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0401, USA

We have investigated a thin layered stack of NiCoO(50nm)/Co(1nm)/Ru using x-ray magnetic circular dichroism (XMCD) and resonant soft x-ray reflectivity (XRMS) at the Ni and Co L2,3 edges. A clear average magnetic Ni spin polarization of 0.037µB has been observed, while the orbital moment is 0.006µB. Assuming that the Ni magnetization is purely located at the first interface layer, it results in an average Ni moment of 0.36µB. The magnitude of the exchange bias effect in the system is strongly increasing for decreasing temperatures. While the Ni moment remains constant when cooling from RT to 80 K, the XMCD related Co moment strongly decreases by 10%, consistent to additional SQUID measurements. Since bulk Co magnetic moments increases for lower temperatures, the observed decrease is interpreted in terms of Co momentum freezing in the antiferromagnetic NiCoO layer. This freezing corresponds quantitatively to the increase of the exchange bias effect.