MEASUREMENT OF THE PERTURBATION OF THE CRYSTAL ELECTRIC FIELD AT PR3+ IN PRNI5 NEXT TO A SINGLE HYDROGEN LIKE INTERSTITIAL

Abstract Muon spin rotation measurements of the temperature dependence and the anisotropy of the μ + Knight shift in single crystals of PrNi 5 reveal pronounced deviations from a linear scaling of the Knight shift with the bulk magnetic susceptibility at T μ + induced modification of the susceptibility of neighbouring Pr 3+ ions. From the Knight shift anisotropy at T 50 K, it is determined that the implanted μ + occupy a single interstitial site, namely the 6i site (0.5, 0, 0.21 ± 0.02), at least below the onset temperature of μ + diffusion T ≈ 150K. Using this site information, good model fits to the experimental data are obtained assuming a μ + induced perturbation of the crystal electric field at the Pr 3+ ions next to the μ + . Apparently, the presence of the μ + leads to a lowering of the local symmetry, causing a lifting of the degeneracy and a pronounced rearrangement of the low lying crystal electric field levels for these ions.