HYPERFINE INTERACTIONS FOR IMPURITY TIN ATOMS IN UCUGE

Hyperfine interactions for Sn-119 atoms are studied in a UCuGe antifer romagnet. Mossbauer absorption spectra are measured in the temperature range 5 - 293 K. At 5 K, the hyperfine magnetic field is B = +/- (62 +/- 2) kOe and the isomeric shift is delta = 1.94 +/- 0.06 mm/s. At 29 3 K, the electric quadrupole constant is found to de e(2)qQ = +/- (1.1 4 +/- 0.12) mm/s. In the temperature range 5 - 35 K, the local magneti c structure of this intermetallic compound remains unchanged, and the mean quadrupole shift amounts to 0.15 +/- 0.02 mm/s. This value corres ponds to an angle of theta = 35 +/- 5 or 90 +/- 10 degrees between the directions of the hyperfine magnetic field B and the gradient of the electric field.