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MA: Fachverband Magnetismus

MA 4: Magnetic Coupling Phenomena/ Exchange Bias

MA 4.5: Vortrag

Montag, 14. März 2011, 12:00–12:15, HSZ 403

Antiferromagnetic coupling in combined Fe/Si/MgO/Fe structures — •Rashid Gareev¹, Frank Stromberg², Werner Keune², Heiko Wende², and Christian Back¹ — ¹Institute of Experimental and Applied Physics, University of Regensburg, Universitätstr. 31, 93053 Regensburg — ²Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Lotharstr.1, 47048 Duisburg

In contrast to antiferromagnetic coupling (AFC) across metallic spacers, the AFC across tunnelling barriers from semiconductor Si [1] or insulator MgO [2] is still under discussion. Fe/Si/Fe structures demonstrate stronger AFC compared to Fe/MgO/Fe but suffer from interface diffusion. In order to decrease interdiffusion we prepared combined epitaxial Fe/Si/MgO/Fe structures with control of interfacial composition by Conversion electron Mössbauer spectroscopy (CEMS). From CEMS with 0.5 nm-thick 57Fe interface markers we detected a continuous reduction of interface diffusion upon increasing the MgO thickness from 0.3nm to 0.5nm for spacers with 0.9 nm-thick Si. MOKE hysteresis confirms AFC for these structures which increases with decrease of MgO thickness above /J/~0.1mJ/m2. Similar structures with pure MgO spacers exhibit only weak 90°- coupling. We conclude that combined Fe/MgO/Fe structures possess enhanced AFC compared to Fe/MgO/Fe and reduced interface diffusion compared to Fe/Si/Fe. This work is supported by the Project DFG 9209379.[1]. R.R. Gareev et al, J. Magn. Magn. Mater. 240, 235 (2002); [2]. J. Faure-Vincent et al, Phys. Rev. Letts 89, 107206 (2002).