Electron spin relaxation of the PO3 2- radical in ferroelectric betaine phosphite and in the proton glass betaine phosphate/betaine phosphite

Abstract

Measurements of the electron spin-lattice relaxation time T1 and the phase memory time TM of the PO3 2- radical in γ-irradiated betaine phosphite and betaine phosphate/betaine phosphite are presented. The temperature dependence of T1 indicates the interaction of the electron spin with two groups of optical branches via Raman processes in both crystals. An additional relaxation path due to the interaction with two-level local tunneling states has been observed in the mixed crystal confirming glassy behaviour. The TM temperature dependence reflects thermally activated local motional effects of the PO3 group in both crystals. © 1994