Quasi-Particle Spectrum around a Single Vortex in Superconductors - s-Wave Case -

Making use of the Bogoliubov-de Gennes equation, we study the quasi-particle spectrum and the vortex core structure of a single vortex in quasi 2D s-wave superconductors for small p_F xi_0, where p_F is the Fermi momentum and xi_0=v_F/Delta_0 is the coherence length (hbar=1). During our numerical calculation the particle number is conserved for each p_F xi_0. In particular, we find that there are only 1 or 2 bound states for p_F xi_0=1. Also, for p_F xi_0=1, the Kramer-Pesch effect ceases to exist at around T/T_c= 0.3.