Thermal dependence of coercivity in soft magnetic nanocrystals

Abstract

An important group of soft magnetic nanocrystals is that formed by \ensuremath{\alpha}-Fe(Si) nanocrystals (around 10-nm grain size) embedded in a residual amorphous matrix. A simple phenomenological theory that takes into account the two-phase character based on the random anisotropy approximation has been developed. The percentage of crystallized material $x$ is taken into account and a quantitative expression for the thermal dependence of coercivity, considering the two-phase character of the samples, has been obtained. The good fit between the experimental curves and the theoretical ones of nanocrystalline ${\mathrm{Fe}}_{73.5}{\mathrm{Si}}_{13.5}{\mathrm{B}}_{9}{\mathrm{Cu}}_{1}{\mathrm{Ta}}_{3}$ samples with different crystallized volume fraction is discussed.