NMR line shapes and order-parameter determination in proton pseudo-spin-glasses

The quadrupole-perturbed NMR line shape has been evaluated in the local approximation for an arbitrary static random-field distribution coexisting with Gaussian time-fluctuating random fields. The special case of a spin-glass-type static local random-field distribution is treated also. The results are compared with some recent experimental data for the deuteron glass ${\mathrm{Rb}}_{1\mathrm{-}\mathit{x}}$(${\mathrm{ND}}_4$ ${)}_{\mathit{x}}$ ${\mathrm{D}}_2$ ${\mathrm{PO}}_4$. They show that by a comparison of experimental and theoretical line shapes in strongly disordered systems, not only the local random-field distribution but also the spin-glass order parameter can be determined.