Microscopic study of the magnetic coupling in a nanocrystalline soft magnet

T Kemény, D Kaptás, J Balogh, LF Kiss, Tamás Pusztai1, I Vincze

1Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest H-1525, Hungary

The magnetic behaviour of nanosize ferromagnetic bcc granules embedded in an amorphous tissue (i.e., partially crystallized Fe80Zr7B12Cu amorphous alloy) was studied by Fe-57 Mossbauer spectroscopy. The results are compared with the bulk counterparts: bcc-Fe and amorphous Fe2B0.625Zr0.375. Size dependent enhancement of the Curie point of the nanosize amorphous phase was not observed. At temperatures well above the Curie point of the amorphous phase superparamagnetic relaxation of the bcc crystallites is observed opening new possibilities to study the anisotropy energy of nanosize ferromagnetic grains.