NMR and the Conduction Electron Polarization in Rare-Earth Metals

The magnitude and sign of the conduction electron polarization in rare earth intermetallic compounds has been determined with the use of NMR techniques. Large, temperature-dependent Knight shifts of the Al27NMR were found in XA12 (X ≡ rare-earth ion). These observations may be explained by assuming that anegative exchange interaction of ∼0.1 ev exists between the localized f electrons of the rare-earth ion and the conduction electrons.