Hybridization Effects on Conduction-Electron Polarization and Two-Ion Coupling in PrCu₂Si₂

Abstract

The temperature dependence and the anisotropy of the magnetic susceptibility and the Knight shifts have been measured in PrCu₂Si₂ and GdCu₂Si₂ with magnetically aligned powder samples. For GdCu₂Si₂, the isotropic s-f exchange model provides a good description of its magnetic properties, but in PrCu₂Si₂ an anisotropic two-ion coupling has been found. It has been revealed that the hyperfine coupling at the Si sites is enhanced in PrCu₂Si₂, thereby suggesting preferential hybridization of the f-electrons with the Si valence electrons. This effect is responsible for the unusually high Neel temperature of PrCu₂Si₂.