Giant voltage response to magnetic field of model granular magnetic films and spin mixing effects

Magneto-thermogalvanic voltage (MTGV) is the magnetic field dependence of the AC voltage measured across a sample subjected to a DC current and to an oscillation of its temperature. Large field sensitivity was found when the measurement was applied to a thin film made by the technique of cluster-assembled materials. [1] Clusters of Co with an average size of 15 atoms per cluster in a copper matrix gave this result. Similar large changes were observed using silver as a matrix. The size of this effect compared to GMR, its temperature and field dependence, in these and other nanostructures, demonstrate that a different process than that responsible for GMR is the determining mechanism. Argument in favour of an asymmetry in the spin mixing process is given. \newline \newline [1] S. Serrano-Guisan et al., \underline {Nature Materials} \textbf{5,} 730 (2006)