Hyperfine fields in Co-based Heusler alloys

The hyperfine fields at Sn, Sb and Hf, respectively have been determined from Moessbauer experiments with 119Sn, 121Sb and 178Hf in Heusler alloys: Co2VSn, Co2NbSn, Co2HfSn, Cosub(2-x)Fesub(x)TiSn (x=0.2,0.4), Cosub(2-x)Nisub(x)TiSn (x=0.1,0.2) and Cosub(2)TiSnsub(0.9)Sbsub(0.1). Moreover, the hyperfine field at Ta on the Hf site in Co2HfSn alloy has been measured by the time differential perturbed angular correlation method. The results are discussed in terms of the electronic structure of these alloys. In particular, the observed anomalies in the tin hyperfine field are explained by the assumption that the polarization of the p-electrons of tin depends decisively on the nature of the neighboring nonmagnetic transition metal atoms