Non-Fermi-liquid nature and exotic thermoelectric power in the heavy-fermion superconductorUBe13

Abstract

We report quite exotic thermoelectric power $S$ in ${\mathrm{UBe}}_{13}$. At 0 T, the negative $S/T$ continues to strongly enhance down to the superconducting transition temperature with no Fermi-liquid behavior. $|S/T|$ is dramatically suppressed and becomes rather modest with increasing field. We have also obtained precise field dependencies of (i) an anomaly in $S$ due to an exotic Kondo effect and (ii) a field-induced anomaly in $S/T$ associated with the anomalous upward ${H}_{\mathrm{c}2}(T)$. In contrast to the field-sensitive transport property, the normal-state specific heat is magnetically robust, indicating that the largeness of the $5f$ density of states remains in high fields. This unusual behavior in ${\mathrm{UBe}}_{13}$ can be explained by a considerable change in the energy derivative of the conduction-electron lifetime ${\ensuremath{\tau}}_{\mathrm{c}}(\ensuremath{\epsilon})$ at the Fermi level under magnetic fields.