Free precession of165Ho nuclei in a single crystal of holmium iron garnet

Abstract

A well resolved seven-line NMR spectrum has been obtained by measuring the frequency dependence of the free precession signal from holmium nuclei, following a pi /2 pulse, in a single crystal of HoIG at 4.2K. The power- and field-dependence of the signals show that they come from nuclei within domains. The zero-field spectrum has been fitted to a nuclear spin Hamiltonian with dipolar, quadrupolar and octupolar terms. From the measured magnetic dipole splitting the authors deduce that the holmium moment at at least one of the two inequivalent crystallographic sites is (8.065+or-0.025) mu B. This result contradicts a recent neutron diffraction study in which the moments assigned to the two sites were (6.0+or-0.5) mu B and (9.9+or-0.5) mu B. Relaxation behaviour of holmium nuclei in the garnet single crystal is contrasted with results previously obtained from a powder sample of HoIG.