Low-temperature calorimetric investigation of Co-Ga spin-glass

Low-temperature specific-heat measurements are presented for the spin-glass alloys ${\mathrm{Co}}_x{\mathrm{Ga}}_{1-x}$ with $x$ between 0.49 and 0.58. For these compositions the antistructure defects are the principal magnetic entities with concentrations in the range 0.9-8.0%. For the high-concentration samples, nuclear Schottky and spin-wave contributions to the specific heat have been identified. Over the entire composition range a term with a linear temperature dependence has been found and is identified with the spin-glass state. Measurements have been taken in magnetic field from 0 to 2.8 T. These data can be understood in terms of a model with a distribution of two-level systems.