Real Space Periodic Electron Density Modulations and Vortex Core Spectroscopy in Heavily Overdoped Bi2Sr2CaCu2O8+δ

We study high temperature superconductivity of heavily overdoped (p~0.22) Bi2Sr2CaCu2O8+d with the objective to find signatures of the more conventional superconductivity anticipated in comparison to its more widely studied underdoped counterpart. We find some similarities as well as distinctly different properties, in particular a short-range static periodic modulation caused by quasiparticle interference (QPI) due to scattering off smooth disorder, without invoking density waves. Our study further lifts a long-standing puzzle about the electronic vortex core structure in this compound. We find convincing evidence that QPI is also responsible for low-energy periodic modulations reported inside vortex cores at high magnetic fields (B=3T). Reducing the applied magnetic field by over an order of magnitude (B=0.16T) nearly completely suppresses QPI and vortex-vortex interactions, revealing spectral signatures in these more isolated vortex cores that are in striking agreement with BCS expectations