Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 4: Magnetic Coupling Phenomena/ Exchange Bias

MA 4.2: Talk

Monday, March 22, 2010, 11:15–11:30, H22

Antiferromagnetic coupling in Fe/Si/Fe structures with interfacial Co ``dusting'' — •Rashid Gareev¹, Matthias Buchmeier², Matthias Kiessling¹, Georg Woltersdorf¹, and Christian Back¹ — ¹Uni Regensburg, Universitätsstrasse 31, 93053 Regensburg — ²Uni Münster, Corrensstraße, 48149 Münster

Epitaxial Fe/Si/Fe structures demonstrate strong antiferromagnetic coupling (AFC) reaching 8mJ/m2 and resonant-type tunnelling magnetoresistance (TMR) [1]. A promising way to increase spin polarization is to insert Co *dusting* layers at interfaces [2]. We present AFC in Fe/Co/Si/Co/Fe epitaxial structures with 0.2 nm-thick Co *dusting* layers and different thickness of Si spacer. We extracted AFC from fitting experimental FMR data as well as from the MOKE hysteresis. The AFC is near 0.1mJ/m2 with the maximum of coupling near 2.0 nm of spacer thickness. For spacers thinner than 1.7 nm coupling is ferromagnetic indicating an increased inter-diffusion. Temperature dependence of magnetization above T0~50K corresponds to the Bloch*s law characteristic for spin-wave parameters of iron films. We revealed regions with different temperature dependence of AFC. Below T0~50K and above T~100K saturation field and, accordingly, coupling strength show increase with decreasing temperature. In the intermediate region coupling is not stable. We relate observed features to formation of interface magnetic iron-cobalt silicides with Tc~50K. This work is supported by the project DFG 9209379.[1]. R.R. Gareev et al: JMMM 240, 235 (2002), APL 81, 1264 (2002), JAP 93, 8038 (2003), APL 88, 172105 (2006); [2]. Y. Wang et al, APL 93, 172501 (2008).