$\beta$ NMR study of Isolated $^8$Li in the enhanced paramagnet Platinum

TL;DR

This study uses beta-detected NMR to investigate how implanted lithium ions affect the magnetic properties of platinum, revealing a local defect response that influences the material's enhanced paramagnetism.

Contribution

It provides new insights into the local magnetic response of platinum to interstitial lithium, highlighting defect-induced modifications in its paramagnetic behavior.

Findings

Spin-lattice relaxation rate and Knight shift depend linearly on temperature.

Knight shift scales with Curie-Weiss susceptibility extrapolated to low T.

Presence of Li+ locally relieves the tendency for susceptibility saturation.

Abstract

We report {\beta} detected nuclear magnetic resonance ({\beta}NMR) measurements of 8Li+ implanted into high purity Pt. The frequency of the 8Li {\beta}NMR resonance and the spin-lattice relaxation rates 1/T1 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 \c{hi} 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+.