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 TC or TN.