Hall effect of sputtered NiZr and CoZr metallic glasses near the critical magnetic concentration

Abstract

With increasing 3d component, the 3d transition-metal Zr amorphous alloys undergo a transition to ferromagnetism at xc=88 at. % Ni, 62 at. % Co, and 38 at. % Fe, respectively. The first two compositions are outside the range of stable melt-spun glasses, but can be prepared by sputtering. In this paper, we present Hall data for sputtered NiZr and CoZr alloys in the vicinity of the critical magnetic composition. For the ferromagnetic glasses, x>xc, the alloys are magnetically soft. Although the NiZr alloys are quite weak magnetically [μ0M(T=0)=0.15 T at 90 at. %], the extraordinary Hall coefficient is very large (Rs=−0.67×10−7 m3/C for the same alloy). In the Co glasses, Rs is positive, but of the same magnitude even though the magnetism is considerably stronger. In the paramagnetic range x<xc, the rapid change in ordinary Hall coefficient close to the critical concentration for ferromagnetism indicates the presence of spin fluctuations, as has been found for the melt-spun FeZr glasses.