β-NMR study of isolated8Li+in the enhanced paramagnet platinum

Abstract

We report β-detected nuclear magnetic resonance (β-NMR) measurements of 8 Li + implanted into high purity Pt. The frequency of the 8 Li β-NMR resonance and the spin-lattice relaxation rates 1/T 1 were measured at temperatures ranging from 3 to 300 K. Remarkably, both the spin-lattice relaxation rate and the Knight shift K depend linearly on temperature T although the bulk susceptibility does not. K is found to scale with the Curie-Weiss dependence of the Pt susceptibility extrapolated to low temperatures. This is attributed to a defect response of the enhanced paramagnetism of Pt, i.e., the presence of the interstitial Li + locally relieves the tendency for the Curie-Weiss susceptibility to saturate at low T . We propose that the low temperature saturation in χ of Pt may be related to an interband coupling between the s and d bands that is disrupted locally by the presence of the Li + .

Local metallic and structural properties of the strongly correlated metal LaNiO3 using 8Li β–NMR

“…However, an essential feature of our data is the two component character of the relaxation indicating two metallic local environments for the 8 Li. Based on the β-NMR of 8 Li in simple metals, 22,38,[42][43][44][45][46] one possibility is simply that there are two inequivalent sites for the implanted 8 Li within the unit cell. In elemental Ag and Au, 22,38,44 for example, there are two cubic 8 Li sites that differ in their hyperfine coupling to the conduction band, and we find a T dependent site change transition around 180 K. 44 In other perovskite oxides, [34][35][36] we find a single interstitial 8 Li + site characterized by a large quadrupole splitting, 34,35,37 which we shall call the P site, at the 3c Wyckoff position in the cubic (Pm 3m) phase.…”

Spin fluctuations in the exotic metallic state ofSr2RuO4studied withβ-NMR

“…1. The relaxation is relatively slow, about half as fast as 8 Li + in Pt at 300 K [27]. Upon cooling, it slows further but remains measurable at 5 K. The data are fit to a single exponential relaxation [exp(−t/T 1 )] convoluted with the beam pulse shape [28] to extract the relaxation rate 1/T 1 plotted in Fig.…”

Comparison of 8Li and 9Li Spin Relaxation in SrTiO3 and Pt: A Means to Distinguish Magnetic and Electric Quadrupolar Sources of Relaxation

“…This discrepancy could be explained by the fact that the measurements were taken at 300 K. At this temperature, the lithium probes could feel a small fluctuating EFG due to phonon-lithium scattering or local lattice vibrations. These effects would give rise to electric quadrupolar relaxation, but the fact that the temperature dependence in this material is known to be linear [18] imposes a strict upper boundary to their relative strength.…”