Electric field dependence of the correlation time of Ag+off-center defects in RbCl

Abstract

Abstract Nuclear spin relaxation measurements can be successfully used to determine the correlation tims τ of the localized motion of dilute centers in alkali halides up to about 10−11 s, as we have demonstrated in previous work. Now, a detailed analysis of the nuclear spin relaxation process is presented, which leads to a BPP type relation between the correlation time T and the motion-induced part of the nuclear spin relaxation rate. Nuclear spin relaxation measurements were carried out on RbCl:Ag+ as a function of a static electric field E applied to different crystallographic directions of the crystal between 1.4 K and 4.2 K. Generally, the interaction of a paraelectric defect with the electric field leads to an increase of the correlation time when increasing the field. An evaluation of the data gives τ = τ (E, T). The results are discussed in terms of phonon-assisted tunneling.