Exchange Constants and Knight-Shift Anisotropy in Single-Crystal Lead

Abstract

Nuclear-magnetic-resonance studies of the angular dependence of the resonance frequency, the linewidth, and the second moment have been made upon a lead single crystal. The "exchange-narrowing" model has been shown to be inapplicable to lead. The angular variation of the second moment has established that the contribution from the second-nearest neighbors is very small and values are obtained for the pseudoexchange and pseudodipolar coefficients for the first-nearest neighbor of ${J}_{1}=4.64$ kHz and ${b}_{1}=1.75$ kHz, in moderate agreement with the theoretical values of Tterlikkis, Mahanti, and Das of ${J}_{1}=4.81$ kHz and ${b}_{1}=1.48$ kHz. A small anisotropy of the Knight shift which has the expected angular dependence has been observed for the first time in a cubic metal.