  We devise a new proximity junction configuration where an s-wave
superconductivity and the superconductivity of Sr2RuO4 interfere with each
other. We reproducibly observe in such a Pb/Ru/Sr2RuO4 junction with a single
Pb electrode that the critical current Ic drops sharply just below the bulk Tc
of Sr2RuO4 and furthermore increases again below a certain temperature below
Tc. In order to explain this extraordinary temperature dependence of Ic, we
propose a competition effect involving topologically distinct superconducting
phases around Ru inclusions. Thus, such a device may be called a "topological
superconducting junction".
