Electron states at superconducting-normal interfaces

Electron states at superconducting-normal interfaces have been studied using Kalkstein-Soven type Green's functions; dispersion curves of interface states and density of states (DOS) curves at various atomic planes are obtained. Two points are worth noticing: (1) there are breaks in the dispersion curves which are absent in normal-normal interface states; (2) on the normal conductor side, the DOS at the first few atomic planes also has the characteristics of the superconductor side