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 behavior of the excitation spectrum in UBe₁₃. With decreasing temperature 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-called Kondo alloys with supposed non-Fermi-liquid behavior at low temperatures. A discussion of our experimental findings with respect to recent theoretical calculations, suggesting the non-Fermi-liquid nature of UBe₁₃, is proposed.