Muon diffusion in the metal hydrides LaNi 5H 6 and β-PdH x

Abstract

Zero- and transverse field muon ( μ +) spin rotation measurements were performed in LaNi 5H 6 and PdH x (0.59 ⩽ x ⩽ 0.86) between 16 K and room temperature. The μ + depolarization is due to the spread in nuclear dipole fields originating predominantly from the protons. Motional averaging is caused by the combined motion of the protons and the β +. The results show a surprisingly low correlation rate 1 τ c which indicates highly correlated μ +-proton diffusion or μ + trapping within regions of largely immobile hydrogen configurations. μ + trapping or a localized μ + jump mode could be considered in LaNi 5H 6 where a linear decrease in the second moment with temperature between 20 and 120 K was measured in contrast with the unchanged relaxation observed by proton magnetic resonance.