Electron Relaxation of Fe Ion in Antiferromagnetic Cobaltous Carbonate

A Mössbauer study of CoC${\mathrm{O}}_3$ doped with ${\mathrm{Fe}}^{57}$ was made above and below the Néel temperature. The magnetic hyperfine field at ${\mathrm{Fe}}^{57}$ nuclei below $T_N$ is observed to be perpendicular to the principal axis of the maximum electric field gradient. Asymmetric line broadening at low temperatures was observed and interpreted in terms of spatial distribution of the average magnetic hyperfine field over the nuclear observation time. $H=72\mathrm{}\pm 2$ kG and $\frac{1}{2}{e}^2\mathrm{qQ}{(1+\frac{1}{3}{\eta }^{\prime 2})}^{\frac{1}{2}}=1.95\mathrm{}\pm 0.04$ mm/sec at 4.9°K were observed.