Effect of d-band mixing in Mn-transition-metal spin glasses.

Abstract

The recently reported magnetic properties of amorphous (a) Mn-Zr alloys exhibited two remarkable and unexpected results. First, while Ni, Co, and Fe display no local magnetic moment when alloyed with Zr in metallic glasses, Mn has a local moment in a--Mn-Zr. Second, the existence of the Mn local moment does not result in a spin-glass interaction. These results can be understood by the study of the magnetic properties of a--Cu-Zr-Mn alloys presented here which shows that the absence of spin-glass interaction in a--Mn-Zr is not due to the amorphous state but to a mixing of the Zr and Mn d bands. This explanation suggests that a spin-glass interaction should exist when the transition-metal host for Mn displays a low density of d states at the Fermi level (${E}_{F}$). Indeed, among transition metals, W has the lowest density of d states at ${E}_{F}$, and W-Mn alloys exhibit a spin-glass transition. The susceptibility of this new spin glass was measured in low ac field and in both low and high dc fields. The spin-freezing temperature (${T}_{\mathrm{SG}}$) increases essentially linearly with Mn content up to 34 at. % Mn where massive antiferromagnetism sets in.