Electrical-resistivity and ac-susceptibility measurements on Ni-Mn and Ni-Mn-Pt ternary alloys

We present electrical-resistivity and ac-susceptibility measurements for both reentrant-spin-glass (RSG) ${\mathrm{Ni}}_{76\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{24}$ ${\mathrm{Pt}}_{\mathit{x}}$ alloys (0<x<3) and pure spin-glass (SG) ${\mathrm{Ni}}_{72\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{28}$ ${\mathrm{Pt}}_{\mathit{x}}$ alloys (0<x<10) in the 4.2–300 K temperature range. The freezing temperature (${\mathit{T}}_{\mathit{g}}$) of the RSG system remains almost constant with nonmagnetic Pt impurity addition, while that of the SG system slightly increases. It is found that the SG alloys exhibit resistivity minima which shift towards higher temperatures with increasing Pt concentrations. However, the minima for the RSG system take place at temperatures below 5 K. It has been found that the resistivity curves for both the SG and RSG systems change slope at temperatures where corresponding ac-susceptibility curves exhibit maxima. These results have been interpreted in terms of domain-anisotropy and Saslow-Parker models.