Josephson effect and point-contact spectroscopy studies of the anomaly observed in the superconducting state of the heavy-fermion compound UBe

Gochi, Jun; Sumiyama, Akihiko*; Yamaguchi, Akira*; Motoyama, Gaku*; Haga, Yoshinori   ; Onuki, Yoshichika

A heavy Fermion compound UBe shows superconductivity below 0.9 K. Earlier study detected an anomaly at 0.7 K deep within the superconducting phase, which was attributed to an additional magnetic phase transition. In this paper, Josephson effect and point-contact spectroscopy have been used to investigate the anomaly in detail. The increase of the Josephson critical current and a continuous drop of the zero-bias conductivity below 0.7 K strongly suggest an enhancement of superconducting order parameter rather than magnetic effects.