Unusual Proximity Effect of d-Wave Superconductivity

A novel proximity effect, that the d-wave superconductivity induces a different symmetric order parameter in the normal metal side, is investigated for the normal metal (N)-d-wave superconductor (S) junction in the clean limit. The induced superconductivity is obtained self-consistently on the basis of the quasi-classical theory and the condition of this effect to occur is clarified. Our result shows that the deformation of the pair amplitude and the direction of the NS boundary with respect to the phase of the d-wave superconductivity are crucial in this phenomenon. A characteristic structure appearing in the local density of states due to this proximity effect is also examined comparing with the conventional case.