Muon knight shift study on the insulating and metallic states in Na-loaded zeolite low-silica X.

It is known that the insulator-metal transition occurs upon loading guest Na atoms into cages of the zeolite low silica X (LSX). In this study, the metallic and insulating phases of this material were investigated by the muon spin rotation (μ SR) method. We succeeded in detecting the muon frequency shift K μ for the insulating and metallic phases in low temperatures, which was not observed in the previous 23 Na-NMR measurements. Contribution to K μ , which is proportional to the density of state at the Fermi energy, is deduced to be 18±2% of that in the bulk metallic Na. [ABSTRACT FROM AUTHOR]