Paramagnetic resonance of Gd in Lu single crystals

The spin resonance of dilute Gd in Lu single crystals has been measured. It shows a single-line spectrum. The field for resonance, as well as the linewidth, change as a function of crystal orientation. The experimental results are concentration independent (unbottlenecked) and can be described by $g=2.10\mathrm{}\left(1\right)\mathrm{}$, a thermal broadening of the linewidth $b=80\mathrm{} \mathrm{}\left(8\right)\mathrm{}$ G/K and an axial crystal field parameter $D=-63\mathrm{}\left(6\right)\mathrm{}$ G. The results are compared with those in Y and Sc.