Nanocrystalline metallic glass-an unusual particulate medium

The expectation that nanocrystalline Fe-based metallic glass may show a variety of magnetic phases is confirmed experimentally. It is shown that, depending on the annealing conditions (resulting in controlled crystallite size as well as the volumetric fraction of the crystalline phase), the particles exhibit superparamagnetic or superferromagnetic behavior at temperatures above the Curie point of the amorphous matrix. At sufficiently low temperatures (around room temperature), the samples behave ferromagnetically as expected for typical nanocrystalline metallic glass.