Anisotropic Broadening of Linewidth in the Paramagnetic Resonance Spectra of Magnetically Dilute Crystals

The effects of mosaic structure on the anisotropic broadening of the linewidth in paramagnetic resonance spectra of dilute crystals is investigated. A general formula for the line shape and the linewidth at half maximum is derived.The half-width of the spectrum of Gd³⁺ in the single crystal of ThO₂ is measured as a function of the angle of the magnetic field with respect to the cubic axes. Good agreement is found with the above theory. The average deviation of the crystallites from the symmetry axis is found to be about 0.12^∘{}. Small deviations from the agreement indicate a compensating defect approximately along the [100] direction which gives rise to a small axial distortion.