Anomalous Magnetization Of Nanoscale Ferromagnet/Normal-Metal Systems: Possible Evidence Of The Electronic Spin Polarization

The magnetization of two nanoscale ferromagnet/normal-metal systems, random mixtures of Ni-Ag and arrays of Co clusters embedded in a Pt matrix, have been studied down to 0.3 K by means of conventional magnetometry and by the extraordinary Hall effect measurements in fields up to 17 T. Unusually high values and an anomalous temperature dependence of the saturated magnetization in the low temperature limit have been found in both systems. We suggest that the phenomenon is evidence of the temperature dependent spin polarization of the conducting electrons in the normal-metal matrix.