Local-Moment Saturation in a Dilute Giant-Moment Alloy

Abstract

We have performed an investigation of the conduction‐electron polarization in the paramagnetic state of dilute alloys of Co and Fe in a host matrix of platinum. This has been done by observing the nuclear magnetic resonance of the platinum host. Our measurements of Knight shift, linewidth, and relaxation time have been made as functions of impurity concentration (0.005–0.1 at. %), temperature (1.4°–300°K), and magnetic field (4–22 kG). We find that for small values of H/T the strength of the interaction between the conduction electrons and the local moments increases linearly with H/T. For higher values of H/T, but before saturation of the Brillouin function is expected to set in, we see a saturation of the linewidth with increasing 1/T, but not as a function of increasing H. We find the net shift of the center of gravity of the line is zero with respect to the Knight shift of pure platinum metal, and that the linewidth increases linearly with impurity concentration. These results provide evidence for interpretation in terms of a Ruderman‐Kittel‐Kasuya‐Yosida interaction and a non‐Brillouin‐function saturation of the local moment.