Influence of Crystalline Imperfections on Spin-Lattice Relaxation in Ruby

Abstract

Measurements have been made of the spin-lattice relaxation times at 35 GHz on specimens of ruby grown from the vapor phase with chromium concentrations from 0.002 to 0.2%. Correlation of these results with x-ray data has shown that in the one-phonon region the relaxation times at 4.2°K depend on the total undulation of the lattice planes within the specimen and that this effect is temperature-dependent. Thus, the magnitude of the relaxation time can be affected by a factor of 2 in typical specimens. The temperature dependence of the relaxation times in the Raman region can be explained using the theory of Castle et al., if two defect sites are assumed. Comparable results are presented for rubies grown by the Verneuil and Czochralski methods.