Impurity and interface bound states in dₓ₂₋y₂+idxy and pₓ+ipy superconductors

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Motivated by recent discoveries of novel superconductors such as NaₓCoO₂· yH₂O and Sr₂RuO₄, we analysize features of quasi-particle scattering due to impurities and interfaces for possible gapful dₓ₂₋y₂+idxy and pₓ+ipy Cooper pairing. A bound state appears near a local impurity, and a band of bound states form near an interface. We obtained analytically the bound state energy, and calculated the space and energy dependent local density of states resolvable by high-resolution scanning tunnelling microscopy. For comparison we also sketch results of impurity and surface states if the pairing is nodal p- or d-wave.