Heat capacity of Heusler alloys: Ferromagnetic Ni2MnSb,Ni2MnSn,NiMnSb and antiferromagnetic CuMnSb

We report the results of the investigation of the specific heat of the ferromagnetic Heusler Ni₂MnSn, Ni₂MnSb, NiMnSb and antiferromagnetic CuMnSb alloys. The low-temperature behaviour of the specific heat may be described as C=γT+βT³ for ferromagnetic compounds and as C=γT+δ T²+βT³ for antiferromagnetic CuMnSb. The values of the density of states from the heat capacity measurements are higher than those from electronic band structure calculations. Debye temperatures are in a good agreement with those obtained from thermal expansion measurements. The Grüneisen parameter is calculated for Ni₂MnSn and CuMnSb from the magnetic contribution to the specific heat in the vicinity of T_C or T_N.