Anomalous Transferred Hyperfine Coupling in CeCu₂Si₂

Abstract

The magnetic susceptibility and the Cu and Si Knight shifts have been measured in CeCu₂Si₂. The transferred hyperfine couplings at both the sites are strongly temperature-dependent and noticeably anisotropic at low temperatures. The negative hyperfine couplings observed for the magnetic field along the c-axis at the low temperatures are anomalous as in Ce intermetallic compounds. It is pointed out that the transferred hyperfine coupling due to the hybridization of the f electrons with the ligand s electrons can be anisotropic and also can reverse its sign at the lower temperatures than the crystal-field splitting energy. It is concluded that this hybridization is the dominant mechanism of the transferred hyperfine coupling and responsible for the anomaly.