PRESSURE-DEPENDENCE OF THE HYPERFINE FIELD OF A CD PROBE IN A RELAXED TRIVACANCY COMPLEX IN NI

Perturbed gamma-gamma-angular-correlation experiments were carried out using extremely dilute Cd-111 probes to measure the pressure dependence of the magnetic hyperfine field at a vacancy-solute complex in Ni in which the Cd probe is relaxed to the center of a tetrahedron of vacancies. The pressure dependence of the hyperfine field of the defect-free substitutional site was found to be dH(hf)/dp = -0.038(6) kG/kbar, which agrees with a previous measurement. The pressure dependence of the hyperfine field associated with the vacancy complex was found to be dH(hf)/dp = -0.023(4) kG/kbar. Results are not found to be consistent with a simple picture of the hyperfine-field-production mechanism obtained from recent first-principles calculations.