Paramagnetic Relaxation ofFe3+in Potassium Cobalticyanide

Relaxation time measurements have been made on the ${\mathrm{Fe}}^{3+}$ ion in ${\mathrm{K}}_3$[Co, Fe]${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_6$ at low temperatures using the saturation-recovery method. Two distinct decay times have been observed; the longer decay time has been interpreted as the true spin-lattice relaxation time $T_1$, while the more rapid initial decay can be explained by a spin-diffusion process (cross-relaxation process) within the inhomogeneously broadened resonance line. The observed temperature dependence of $T_1$ indicates that the Raman type of interaction dominates the relaxation process near 4.2°K while a $\frac{1}{T}$ law of the simple "direct process" model is predominant at temperatures below 1.8°K. For iron concentrations between 0.1% and 3.0% the spin-lattice relaxation time was found to be nearly independent of concentration.