SPECIFIC-HEAT OF NI-2(NB1-XTX)SN, T=TI,TA, SUPERCONDUCTING HEUSLER COMPOUNDS

We present the results of low-temperature (1.5-10 K) specific heat mea surements of superconducting Heusler compounds Ni-2(Nb1-xTx)Sn, (T = T i, Ta, and x = 0, 0.05, 0.10 and 0.20). All the compounds exhibit latt ice anomalies, reflected in the specific heat by the relevance of an E instein term. The decrease in the superconducting transition temperatu re with increasing concentration is correlated with changes in the ele ctron-phonon interaction.