Reentrant spin-glass-like behavior as a consequence of constrained dynamics of magnetic clusters: a case study of Fe_1.4Ru_1.6Si

Abstract

The identification of two distinct transitions in random magnetic systems as predicted by the Gabay-Toulouse model has received considerable support from ⁵⁷Fe Mossbauer data in Fe-based reentrant spin-glass systems. Alternatively, it has been argued that the apparent multiple-transition behavior of reentrant spin-glass alloys is a consequence of the dynamics of interacting magnetic clusters. In this picture no well-defined phase changes are expected. We present here the results of bulk-magnetic-response and ⁵⁷ssbauer studies in a new random magnetic system, Fe_1.4Ru_1.6Si, which shows several features akin to reentrant spin glasses. The data in this system cannot be reconciled in terms of two transitions corresponding to the freezing-in of transverse and longitudinal components of the magnetic moment. Instead, our data suggest that the slowing down of spin dynamics is a continuous process, and the features that identify the reentrant spin-glass phase arise from the dynamics of mutually constrained magnetic clusters.