Low-energy structures in vortex core tunneling spectra in Bi2Sr2CaCu2O8+δ

Scanning tunneling spectroscopy allows us to study the changes in the quasiparticle local density of states due to the presence of vortex cores in Bi2Sr2CaCu2O8+delta (BSCCO). The vortex core spectra are characterized by a gap-like structure similar to the pseudogap measured above T-c. We also observe small spectral structures inside the gap in the vortex cores. The observed low-energy structures are weaker than what one expects for localized quasiparticle excitations. (C) 2000 Elsevier Science B.V. All rights reserved.