The atomic volume V a-Fe that can be assigned to Fe atoms in Fe-metalloid (Fe-MD) and Fe-early transition metal (Fe-TE) glasses was deduced in a previous paper (I. Bakonyi, Acta Materialia 53 (2005) 2509) from an analysis of available density data for such amorphous alloys. In the present paper, based on a similarity of the amorphous and face-centered cubic (fcc) structures, the distinctly different magnetic behaviors of these two families of amorphous alloys are discussed in terms of the relative position of V a-Fe and the critical volume V fcc-Fe≈11.7 Å 3/atom separating the so-called low-spin (LS) and high-spin (HS) state of fcc-Fe. For Fe-MD systems, V a-Fe is found to be definitely larger than V fcc (*)-Fe whereas for Fe-TE systems V a-Fe is fairly close to V fcc (*)-Fe. Since in topologically disordered alloys a distribution of atomic volumes is inherently present, in Fe-MD glasses the Fe atoms can be assumed to exhibit exclusively the HS state whereas in Fe-TE amorphous alloys a comparable fraction of Fe atoms can be either in the LS or the HS state. According to previous theoretical band structure calculations, an antiferromagnetic state can also be stable just around V fcc (*)-Fe. The simultaneous presence of Fe atoms with such a rich variety of magnetic states due to the specific position of the average of the atomic volume distribution can well explain the complex magnetic behavior observed in Fe-rich Fe-TE metallic glasses such as, e.g., in amorphous Fe-Zr alloys around 90 at% Fe.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics