Spin-Lattice Relaxation ofMn2+in Hexagonal CdS below 4.2 °K

Abstract

The spin-lattice relaxation of ${\mathrm{Mn}}^{2+}$ in hexagonal CdS has been studied at $X$ band in the temperature range 1.3-4.2 °K using inversion-recovery techniques. The transient recoveries of several of the fine-structure lines to thermal equilibrium were monitored following several different initial perturbations of the level populations. In each case the recovery was found to proceed via the direct absorption and emission of phonons over this temperature range. The $\Delta M=\pm 2$ spin-phonon transition rates were found to be more than an order of magnitude faster than the $\Delta M=\pm 1$ rates. No evidence of cross-relaxation effects were found. The superhyperfine coupling to the nearest-neighbor ${\mathrm{S}}^{33}$ nuclei was determined by hole-burning techniques to be 0.5 × ${10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$.