The evidence for anisotropic rare-earth-conduction electron interactions

The rare-earth-conduction electron interaction has anisotropic as well as isotropic components. We exhibit the form these interactions take and discuss the experimental evidence for the existence of anisotropic interactions. Experimental data are presented on the magneto-transport properties, spin resonance, and thermoelectric power of rare-earth impurities in metals and rare-earth intermetallic compounds. The anisotropic terms are as large as the isotropic ones for some of the rare-earths