Interband proximity effect and nodes of superconducting gap in Sr2RuO4 - art. no. 057001

The power-law temperature dependences of the specific heat. the nuclear rel axation rate, and the thermal conductivity suggest the presence of line nod es in the superconducting gap of Sr2RuO4. These recent experimental observa tions contradict the scenario of a nodeless (k(x) + ik(y))-type superconduc ting order parameter. We propose that interaction of superconducting order parameters on different sheets of the Fermi surface is a key to understandi ng the above discrepancy. A full gap exists in the active band, which drive s the superconducting instability, while line nodes develop in passive band s by the interband proximity effect.