Pulsed nuclear magnetic resonance and nuclear spin dynamics in AlP

Pulsed-nuclear-magnetic-resonance measurements are reported in powdered AlP. Measurements of the second moment of ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ indicate that the dominant ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$-${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ interaction is 20% smaller than the calculated dipolar value. The reduction is interpreted in terms of an interference effect of the pseudodipolar interaction. A broadening of the ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ resonance is observed and found to arise from the first-order quadrupolar interaction. Nuclear spin-lattice relaxation of Al${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ is studied at 4.2, 78, and 300 K. Paramagnetic centers appear to be responsible for relaxing the ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ nuclei at the higher temperatures. A rotating-frame multiple-pulse double-resonance experiment is used to study the evolution of the ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ magnetization along the effective field under the simultaneous irradiation of a second ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ resonant rf field. A cross-relaxation model adopted can be used to describe one of the results reported in earlier rotating-sample experiments on AlP.