Quadrupole Influence on the Dipolar-Field Width for a Single Interstitial in a Metal Crystal

The dipolar broadening of the magnetic field sensed by an interstitial impurity in a rigid lattice is calculated with the electric-field gradient set up by the impurity taken into account. This is shown to give a strong dependence of the dipolar width on the applied magnetic field. The theory is especially applicable to the linewidth of precessing muons in metals.