ANDREEV BOUND STATES, SURFACES AND SUBDOMINANT PAIRING IN

Abstract—A characteristic feature of the BCS theory of superconductivity is the quantum-mechanical coherence of particle and hole states. Direct observation of particle-hole coherence in unusual superconducting materials is a strong indicationof traditionalsuperconductivity.Weuse theFermi liquid theoryofsuperconductivity tostudythe implications of particle-hole coherence on properties of d-wave superconductors near surfaces. Typical surface phenomena are the suppression of the superconducting order parameter, surface bound states associated with Andreev reflection, anomalous screening currents, and spontaneous breaking of time-reversal symmetry. We review these phenomen