POINT-CONTACT SPECTROSCOPY OF YBBE13

Among rare-earth and actinide Be-13 intermetallic compounds, YbBe13 is anomalous, with evidence for mixed-valence and heavy-fermion behavior . The resistivity is comparatively low and the resulting large mean fr ee path enables point-contact spectroscopy in the ballistic regime. In the d(2)V/dI(2) characteristics of point contacts between YbBe13 and normal metals, measured at temperatures between 0.2 and 40 K, we find structures due to crystal-field and Kondo scattering. The characterist ics show a pronounced asymmetry, which we explain by the enhanced effe ctive electronic mass in YbBe13 and by a shift of the chemical potenti al in the contact region due to the nonthermal occupation of excited c rystal-field levels.