NMR lineshapes 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 Rbi_x(ND4 ) xD2P04 . 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.