Paramagnetic Resonance Linewidths in Some Rare-Earth Double Nitrates

Abstract

We have measured the paramagnetic resonance linewidth $\ensuremath{\delta}H$ at microwave frequencies for the three trivalent rare-earth ions Ce, Nd, and Sm present in small concentrations in ${\mathrm{La}}_{2}$${\mathrm{Mg}}_{3}$${(\mathrm{N}{\mathrm{O}}_{3})}_{12}$\ifmmode\cdot\else\textperiodcentered\fi{}24${\mathrm{H}}_{2}$O. The linewidths appear to be strongly dependent upon the angle $\ensuremath{\theta}$ between the $c$ axis of the crystal and the magnetic field, and in most cases the observed linewidths seem to be reasonably well explained by a simple theory which assumes a spatial distribution of paramagnetic resonance $g$ values throughout the crystal.