Specific Heat of Insulating Spin-Glasses, (Eu,Sr)S, near the Onset of Ferromagnetism

Abstract

The specific heat, $C(T)$, of the insulating spin-glass ${\mathrm{Eu}}_{x}{\mathrm{Sr}}_{1\ensuremath{-}x}\mathrm{S}$ with $x=0.40$ exhibits a linear term $\ensuremath{\gamma}T$ and no singularity at ${T}_{f}$, like metallic spin-glasses. A new term, $\ensuremath{\delta}{T}^{\ensuremath{-}2}$, is found which may arise from totally decoupled clusters created by frustration. The field dependence, $\ensuremath{\gamma}(B)$ and $\ensuremath{\delta}(B)$, show maxima. With $x=0.54$ the behavior is similar. $C(T, B)$ and $\ensuremath{\chi}(T, B)$ there indicate the spin-glass phase to be supressed at $B=1$ T.