Abstract: High field magnetoresistance studies in some amorphous metal‐metalloid systems

Abstract
We report the first extensive magnetoresistance, (MR), studies on some amorphous transition metal‐metalloid systems in applied fields, B, to 22 T and for temperatures above 0.1 K. Specifically, we discuss our results on the alloys (T1−xNix)75(PBAl)25, where T=Fe(Co) and x=0.5(0.8). In both these alloys the observed resistance minimum (at 14 K and 39.8 K resp.) is suppressed (by 3 K and 1.8 K resp.) in B as low as 0.56T. There is a strong T‐dependence in the (MR), which can be as large as −0.4%, over a wide temperature range [0.01cc the curvature of the B dependence of (MR) indicates effects of clustering. At 4K in the Co‐Ni alloy we observe a +ve (MR) which after a sharp initial increase remains a constant (+10−5) to B=10T, and then increases linearly at 0.8×10−4/T at higher fields. Such a linear dependence is not observed for the Fe‐Ni alloy. Clearly, the magnetic contribution to the T‐dependence of the resistivity is indeed significant, and is consistent with the broad distribution of fields in these glassy systems.