The magnetic hyperfine field and the electric field gradient at181Ta impurities in Gd metal

Abstract

The magnetic hyperfine fieldHhf and the electric field gradientVzz 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(TaGd; 77 K)|=285(14)kG, and |Vzz(TaGd; 330 K)|=5.32(15)·1017V/cm2. The value ofHhf 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.