Host Nuclear Resonance in a Spin-Glass:CuMn

Abstract

The host ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ NMR in ${\mathrm{Cu}}_{1-c}{\mathrm{Mn}}_c$ alloys with $c$ in the range 1000-4000 ppm exhibits loss of intensity but no abrupt increase in linewidth below the spin-glass ordering temperature $T_0$, in disagreement with theoretical predictions of cooperative "freezing" of the impurity-spin reorientation. Decreases of longitudinal and transverse NMR relaxation times below $T_0$ indicate important modifications of impurity-spin dynamics.