POSSIBLE NON-FERMI-LIQUID NATURE OF PARAMAGNETIC UBE13 - THE OPTICAL POINT-OF-VIEW

Optical investigations over a broad spectral range, extending from the far infrared up to the ultraviolet, reveal a peculiar and anomalous b ehavior of the excitation spectrum in UBe13. With decreasing temperatu re down to 1.8 K a suppression of the Drude weight and a mid-infrared absorption are observed, similar to the optical properties of the so-c alled Kondo alloys with supposed non-Fermi-liquid behavior at low temp eratures. A discussion of our experimental findings with respect to re cent theoretical calculations, suggesting the non-Fermi-liquid nature of UBe13 is proposed. [S0163-1829(97)52340-X].