Theory of charge transport in high-TC superconductor junctions from the view point of the mid gap Andreev resonant state

In this paper, we report important features about high-TC superconductor junctions. It has been clarified that the most important property of high-TC junctions is the sign change of the pair potential on the Fermi surface reflecting on the d-wave pair potential. This unique feature induces the formation of the mid gap Andreev resonant state (MARS) at the interface of the high-TC superconductor junctions. The MARS influences various physical quantities, e.g., quasiparticle current, Josephson effect and proximity effect. In d-wave superconductor, the MARS competes with the proximity effect. On the other hand, for triplet superconductor junctions, it can coexist. We can expect giant proximity effect enhanced by the MARS.