MAGNETIC HYPERFINE FIELD AND THE ELECTRIC-FIELD GRADIENT AT TA-181 IMPURITIES IN GD METAL

The magnetic hyperfine field Hhf and the electric field gradient Vzz at181Ta impurties in metallic Gd were determined by time differential perturbed angular correlation measurements with the 133 keV K-conversion electron 482 keV γ-cascade of181Ta. The sources for these measurements were prepared by implantation of radioactive181Hf ions into Gd. The results are: |Hhf(Ta Gd; 77 K)|=285(14)kG, and |Vzz(Ta Gd; 330 K)|=5.32(15)·1017V/cm2. The value of Hhf fits well into the systematics for 5d impurities in Gd and indicates a positive core polarisation contribution, which is expected if the conduction electrons of Gd have to a large extent d-character. The electric field gradients of the 5d impurities in Gd are not consistent with a proportionality between the ionic and the electronic contribution. © 1979 North-Holland Publishing Company.