INVESTIGATION OF THE MAGNETIC HYPERFINE FIELD AT THE Y-SITE IN THE HEUSLER ALLOYS CO(2)Y(1-X)(1)Y(X)(2)Z (Y=TI, V, NB,CR, Z=AL, SN)

The magnetic hyperfine field (mhf) acting on a Ta-181 probe dilutely s ubstituted at the non-magnetic transition element site has been invest igated for the pseudo-quaternary Heusler alloys Co2Ti1-xNbxAl, Co2Ti1- xVxAl, Co2Ti1-xVxSn, and Co2V1-xCrxAl with x = 0.2,0.4,0.6 and 0.8 by TDPAC measurements utilizing the 133-482 keV gamma-gamma cascade in Ta -181 following the beta(-)-decay of Hf-181. Magnetization measurements on Co2Ti1-x(Nb, V)(x)Al samples were carried out by using a vibrating -sample magnetometer. The Curie temperature and the saturation magneti zation were obtained for each alloy. The lattice parameters of the all oys were determined by x-ray diffraction measurements. The results for the mhf acting on Ta occupying the non-magnetic transition element si te are discussed and compared with the mhf systematics for the cobalt- based Heusler alloys.