The temperature dependence of the linewidth of iron group ions in MgO

The linewidths of the paramagnetic resonance lines of Fe1+, Fe3+ and Mn2+ in MgO decrease as a function of increasing temperature in the helium range. This decrease appears to result from a motional narrowing of the contribution to the linewidth from dipolar interaction with Fe2+ ions as the Fe2+ relaxation rate becomes comparable with the frequency width of the line studied. © 1972.