Fe-Ag multilayers were prepared by vacuum evaporation in a wide range of Fe and Ag thicknesses (tFe, tAg) and bilayer numbers (n), while the magnetic properties as a function of these parameters were measured. Samples with discontinuous Fe layers are superparamagnetic (SPM) and our paper shows that tAg and n affect the superparamagnetic blocking temperature (TB) not only by affecting the interactions between the Fe grains but also through influencing the growth process of Fe and thereby modifying the magnetic-grain-size distribution. A magnetic "phase diagram" of our Fe-Ag multilayers is constructed in the tFe, tAg, n parameter space, where the SPM and ferromagnetic behaviors are separated by a mixed zone showing the characteristics of both. The measured trend of the susceptibilities attained at the blocking temperature (TB), increasing with increasing TB, was explained by the volume distribution of the magnetic particles, as illustrated by calculations for an ensemble of interaction-free magnetic particles.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics