Nuclear Magnetic Resonance ofCo59in DiluteAuCoAlloys

Abstract

Measurements of ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$ NMR shifts and spin-relaxation rates in $\mathrm{Au}\mathrm{Co}$ confirm the nonmagnetic character of isolated cobalt impurities in gold. In the temperature range 1.2-4.0 °K, a large positive resonance shift [$K=+(29.2\mathrm{}\pm 0.2)\%$] is observed, indicative of a dominant orbital hyperfine interaction. The absence of a strong temperature dependence of the shift below 300 °K gives evidence for a high spin-fluctuation temperature. Low-temperature measurements of the spin-echo phase-memory time $T_2$ yield a value $T_{1}T=2.7\mathrm{}\pm 0.5$ msec °K for the spin-lattice relaxation time. The results of the present study illustrate the strong influence of orbital degeneracy on the magnetic properties of cobalt impurities in metals.