Applications of time-differential perturbed angular correlations to the study of solids

Abstract

Time-differential perturbed angular correlation techniques were applied to a systematic study of insulating antiferromagnets and rare-earth intermetallic alloys doped with either /sup 111m/Cd or $sup 111$In. The internal magnetic fields and electric field gradients at the radioactive nucleus are deduced from the experimentally measured perturbation factors. The analysis of fluoride, chloride, oxide, and sulfide data shows the systematic variation of the observed supertransferred hyperfine fields with the intervening anion covalency and allows extraction of covalency parameters after the adoption of a simple model. A comparison of the transferred hyperfine field data between fluoride perovskites and the corresponding quadratic layer compounds produces a value for the zero- point spin deviation in magnetically two-dimensional antiferromagnets which is in qualitative agreement with existing theoretical estimates. Paramagnetic shifts due to transferred hyperfine field and field-induced spin-flopping have also been observed. By careful temperature regulation the temperature dependence of the sublattice magnetization can be plotted next to a diamagnetic impurity in RbMnF$sub 3$ and MnF$sub 2$. A shift in the transferred hyperfine field at Cd doped into MnS has been measured under the application of moderate pressures up to 22 kbar. Analysis of the electric field gradients at the In and Sn sites in the rare-earth series RIn$sub 3$ and RSn$sub 3$ as functions of temperature and pressure is the basis of a check for valence fluctuations in certain of these alloys. (auth)