Oscillatory Curie temperature in ultrathin ferromagnets: experimental evidence

The Curie temperature of low-dimensional ferromagnets can be tailored via finite-size effects, magnetic anisotropoes, as well as by the indirect interlayer exchange coupling in magnetic multilayers, which is of importance not only for fundamental research but also for technological applications. We...

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Published in:Journal of magnetism and magnetic materials 2005-01, Vol.285 (1-2), p.95-100
Main Authors: Rüdt, C., Scherz, A., Baberschke, K.
Format: Article
Language:English
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Summary:The Curie temperature of low-dimensional ferromagnets can be tailored via finite-size effects, magnetic anisotropoes, as well as by the indirect interlayer exchange coupling in magnetic multilayers, which is of importance not only for fundamental research but also for technological applications. We determined the Curie temperature Tc for 2-3 mono layers of Co/Cu(100) as a function of Cu-cap thickness by means of temperature-dependent measurements of the initial zero-field AC susceptibility. We see a strong reduction of Tc that we discuss in terms of hybridization effects and modifications of the electronic structure of Cu. In addition, we found a small oscillatory contribution that reflects an indirect exchange interaction Jcap in the ultrathin Co films mediated by quantum-well states in the nonmagnetic Cu overlayer. We estimate that Jcap is of the order of 2 meV/atom which corresponds to an oscillation amplitude of 4 K as observed in our experiment.
ISSN:0304-8853
DOI:10.1016/j.jmmm.2004.07.021