Paramagnetism of two-dimensional quantum dots with superconducting core

We study orbital magnetism of a mesoscopic superconductor/normal metal hybrid system. We especially consider a two-dimensional normal metal quantum dot with superconducting core. The Bogoliubov–de Gennes equation is solved numerically and the energy levels of the quasiparticle are obtained. It is found that characteristic energy levels appear below the superconducting gap and make significant paramagnetic contributions to the magnetization. We also estimate these subgap levels analytically by using the WKB approximation and clarify their physical properties.