NMR Studies of Dilute Alloys of Ni in Cu

Abstract

We have studied the nuclear magnetic resonance of Cu atoms which are near neighbors to Ni atoms in dilute $\mathrm{Cu}$ Ni alloys. The experiments were performed at liquid-helium temperatures and at magnetic fields from 6 to 60 kG. The resonances show up as weak satellites to the main absorption of more distant Cu. By varying the magnetic field, we can show that several lines arise from a single shell of neighbors having a quadrupole coupling ${\nu }_1=1.1\mathrm{}\pm 0.1$ MHz, asymmetry parameter $\eta =0.20\mathrm{}\pm 0.05$, and a magnetic shift $\frac{\Delta H}{H}=-0.27\mathrm{}\times {10}^{-3\mathrm{}}$. Comparing the quadrupole coupling with estimates made by Béal-Monod and Tompa for CuNi by measuring wipe-out number, we conclude the lines arise from first neighbors. The magnetic shift is smaller than we had previously observed for CuCo in almost exactly the ratio of the $\chi J$'s of the two impurities, where $\chi$ is the impurity susceptibility and $J$ is the $s-d$ exchange coupling.