Contribution of Conduction-Electron Redistribution to Quadrupole Interactions in Plastically Deformed Copper

Abstract

Quadrupole effects due to electric field gradients associated with dislocations in cubic metals are treated and applied to the experimental nuclear-magnetic-resonance results of Faulkner in plastically deformed copper. A new theory of the second moment, which takes into account not only the asymmetric character of the strain field of a screw dislocation, but also the contribution due to the long-range charge-density oscillation of the conduction electrons around it, is developed. It has been found that the use of both strain and charge effects can quantitatively explain many of the discrepancies between the experimental results and the strain-only theory of Watkins and Bloembergen. The effect of dislocation cell structure on the second moment of the ${\mathrm{Cu}}^{63}$ nuclear-magnetic-resonance line broadening due to first-order quadrupole interaction is also discussed. The contribution due to the charge effect is about 20% of the total at high values of deformation in copper.