Specific heat of spin-glass CuMn below 3 K

Abstract

Measurements in the 0.35 to 3 K temperature range on alloys containing 0.083, 0.20, 0.43, 0.88, and 0.92 at.% Mn are reported. The spin-glass contribution to the specific heat does not show a linear dependence on absolute temperature but has an initial positive curvature leading to a linear region which extrapolates back to zero at a positive temperature, dependent on the Mn content. A change in $\frac{d\left(\frac{C_p}{T}\right)}{\mathrm{dT}}$ at the estimated spin-glass freezing temperature was observed for the 0.083 at.% Mn alloy. The estimated freezing temperatures for the other alloys lie outside the range of the present measurements. The results do not obey the simple scaling law $\frac{C_p}{c}=f\left(\frac{T}{c}\right)$, where $c$ is the Mn concentration. However, they are in agreement with earlier specific-heat results below 1 K and recent data above 2 K and also with some recent theory.