Tunneling conductance of normal metal/dx2−y2-wave superconductor junctions in the presence of broken time-reversal symmetry states near interfaces

Abstract

In order to clarify the influence of (the presence of) the broken time-reversal symmetry state (BTRSS) induced near the interface, tunneling conductance spectra in normal metal/${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave superconductor junctions are calculated on the basis of the quasiclassical Green's function method. The spatial dependence of the pair potential in the superconductor side is determined self-consistently. We discuss two types of the symmetry on the BTRSS: (i) ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}+is$-wave state and (ii) ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}{+id}_{\mathrm{xy}}$-wave state. It is shown that the amplitude of the subdominant component $(is$ wave or ${\mathrm{id}}_{\mathrm{xy}}$ wave) is quite sensitive to the transmission coefficient of the junction. As the results, the splitting of the zero-bias conductance peak due to the BTRSS inducement is detectable only at junctions with small transmission coefficients for both cases. When the transmission coefficients are relatively large, the explicit peak splitting does not occur and the difference in the two cases appears in the height of the zero-bias peaks.