NMR study of copper with titanium impurities

Abstract

We present results of an NMR study of copper containing titanium impurities. Satellites from a near-neighbor copper shell to the impurities were detected which possess a quadrupole coupling of ${\ensuremath{\nu}}_{Q}=1.20\ifmmode\pm\else\textpm\fi{}0.01$ MHz, asymmetry parameter $\ensuremath{\eta}\ensuremath{\le}0.08$, and magnetic shift $\frac{\ensuremath{\Delta}K}{K}=\ensuremath{-}0.23\ifmmode\pm\else\textpm\fi{}0.01$. These values are compared with those of other $3d$ transition impurities in copper to show that the satellite is either a first neighbor, in which case $\ensuremath{\eta}$ is unusually small, or a second neighbor. If the latter case is correct, the data show the spin density is reversed relative to its value at second neighbors to iron-group atoms at the right-hand side of the Periodic Table. We have observed first-order quadrupole "wings" whose positions are concentration dependent, and present a simple analysis of the "wings." We have measured the magnetic broadening of the $^{63}\mathrm{Cu}$ main line at high fields. The data suggest that Ti impurities have a larger $s$-$d$ exchange coupling $J$ than Ni.