Edge currents in superconductors with a broken time-reversal symmetry

We analyze edge currents and edge bands at the surface of a time-reversal symmetry breaking d(x2-y2)+id(xy) superconductor. We show that the currents have large Friedel oscillations with two interfering frequencies: root 2k(F) from subgap states, and 2k(F) from the continuum. The results are based independently on a self-consistent slave-boson mean-field theory for the t-J model on a triangular lattice, and on a T-matrix scattering theory calculation. The shape of the edge-state band, as well as the particular frequency root 2k(F) of the Friedel oscillations, are attributes unique for the d(x2-y2)+id(xy) case, and may be used as a fingerprint for its identification. Extensions to different time-reversal symmetry breaking superconductors can be achieved within the same approach.