O. Kanert et al., STUDY OF LOW-FREQUENCY EXCITATIONS IN DISORDERED SOLIDS BY NUCLEAR-MAGNETIC-RESONANCE AND ELECTRICAL-CONDUCTIVITY, Journal of non-crystalline solids, 172, 1994, pp. 1277-1284
Nuclear spin relaxation (NSR) and electrical conductivity observed in
various inorganic oxide glasses at low temperatures are found to be re
lated by the fluctuation-dissipation theorem indicating a common physi
cal origin of the relaxation mechanism due to fluctuating charges whic
h belong to structural low-energy configurations intrinsic to the glas
sy state. However, in heavy metal fluoride glasses, NSR is shown to de
tect additional fluctuations which are not observed by conductivity ex
periments. The underlying relaxation process is caused by magnetic flu
ctuations without any accompanying charge motions.