Investigation of dislocation movement by nuclear-spin-relaxation experiments in the rotating frame

Dislocations moving at various velocities in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$Cl and ${}_{}{}^{87}{}_{}{}^{}\mathrm{Rb}$Cl single crystals were studied by means of the spin-locking technique. The resulting spin-lattice relaxation time in the rotating frame $T_{1\rho }$ is strongly dependent on the plastic-deformation rate $\epsilon$ and the quadrupole moments of the spins considered. The experimental results are in accord with a theoretical expression for $T_{1\rho }$ based on an adaption of the relaxation model of Rowland and Fradin for atomic diffusion. Application of this theory leads to a "mean free path" of a moving dislocation which is determined by the distance between the forest dislocations; this agrees with the value obtained for the strain-rate sensitivity. The range of validity of the adapted Rowland and Fradin model is discussed.