Magnetic scattering effects on quantum transport in a normal-metal–superconductor junction

Within a scattering formalism, the magnetic scattering effects on the transport properties of a normal metal attached to a d-wave as well as an s-wave superconductor have been studied by inserting (i) a Kondo-like magnetic barrier and (ii) a ferromagnetic scattering layer into the normal conducting region. It is shown that, in contrary to our intuition, the Kondo-like magnetic scattering effect is quite similar to the effect of nonmagnetic scattering. Remarkably, the ferromagnetic exchange interaction could lead to the strong resemblance of the conductance behavior between a normal-metal–s-wave superconductor junction containing a ferromagnet layer and a normal-metal–d-wave superconductor with a nonmagnetic scattering layer, and vice versa. This result may complicate significantly the decisive determination of the pairing symmetry in high-T_c superconductors by the quasiparticle tunneling into the superconductor. In addition, the resonance peak splitting in the conductance is exhibited if the ferromagnet layer is located several superconducting coherence lengths away from the normal-metal–superconductor interface.