Correspondence between nuclear-spin relaxation and electrical conductivity in glasses at low temperatures

Abstract

Nuclear-spin relaxation (NSR) and electrical conductivity observed in various inorganic oxide glasses at low temperatures are found to be related by the fluctuation-dissipation theorem, indicating a common physical origin of the relaxation mechanism due to fluctuating charges. However, in heavy-metal fluoride glasses NSR is shown to detect additional fluctuations which are not observed by counductivity experiments. The underlying relaxation process is caused by magnetic fluctuations without any accompanying charge motions.