Existence of the spin-glass state in amorphous Fe.

Abstract

The volume dependence of magnetic properties in amorphous Fe has been calculated on the basis of the finite-temperature theory of amorphous metallic magnetism which self-consistently determines the distribution of local magnetic moments. The calculated magnetic phase diagram on the T-V plane and magnetization-vs-volume curve show the existence of the spin-glass state in a wide range of volume (10.50 A${\mathrm{\r{}}}^{3}$\ensuremath{\lesssim}V\ensuremath{\lesssim}12.5 A${\mathrm{\r{}}}^{3}$) after disappearance of ferromagnetism. The results verify our previous conclusion of the spin-glass state in amorphous Fe, which is expected from the experimental data of Fe-rich amorphous alloys containing early transition metals and rare-earth metals, but disagree with those obtained from the supercell approaches in the ground-state electronic structure calculations. It is shown that the nonlinear magnetic couplings between the nearest-neighbor Fe local moments and the local environment effects on the amplitude of Fe local moments via structural disorder lead to the spin-glass state in the weak magnetic region, while the volume expansion develops the ferromagnetic couplings and therefore the ferromagnetism.