title: Fourfold structure of vortex-core states in Bi2Sr2CaCu2O8+delta.
abstract: We present a detailed study of vortex-core spectroscopy in slightly overdoped Bi2Sr2CaCu2O8+delta using a low-temperature scanning tunneling microscope. Inside the vortex core, we observe a fourfold symmetric modulation of the local density of states with an energy-independent period of (4.3 +/- 0.3)a0. Furthermore, we demonstrate that this square modulation is related to the vortex-core states which are located at +/-6 meV. Since the core-state energy is proportional to the superconducting gap magnitude , our results strongly suggest the existence of a direct relation between the superconducting state and the local electronic modulations in the vortex core.
authors.affiliation: DPMC, Université de Genève, 24 Quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland. giorgio.levy@physics.unige.ch
authors.forename: Giorgio
authors.initials: G
authors.lastname: Levy
authors.forename: Martin
authors.initials: M
authors.lastname: Kugler
authors.forename: Alfred A
authors.initials: AA
authors.lastname: Manuel
authors.forename: Oystein
authors.initials: O
authors.lastname: Fischer
authors.forename: Ming
authors.initials: M
authors.lastname: Li