Observation of Andreev surface bound states in the 3-K phase region of Sr2RuO4 -: art. no. 037003

The tunneling spectrum of the superconducting phase with T-c similar or equal to 3.0 K has been measured in the Ru-embedded region of Sr2RuO4 using cleaved junctions. A sharp zero-bias conductance peak (ZBCP) has been observed below 3 K. All characteristics of this ZBCP suggest that it originates from Andreev surface bound states, indicating that the pairing in the 3-K phase is also non-s-wave. Below the bulk T-c of Sr2RuO4 (similar or equal to 1.5 K), a crossover from sharp to bell-shaped ZBCP was found. This supports the theory that there is a phase transition in the 3-K phase region near the bulk T-c.