Making use of the Bogoliubov-de Gennes equation for the d-wave
superconductors, we investigate the quasi-particle spectrum around a single
vortex. Taking pF​ξ=10, we found that there are bound states which are
localized around the vortex core, and extended states which are rather uniform,
for ∣E∣<Δ where E is the quasi-particle energy and Δ is the
asymptotic value of the order parameter for away from the vortex.Comment: 4 pages, 6 figure