Intrinsic Electronic Structure and Nodeless Superconducting Gap of $\mathrm{YBa_{2} Cu_{3} O_{7-\delta} }$ Observed by Spatially-Resolved Laser-Based Angle Resolved Photoemission Spectroscopy

Abstract

The spatially-resolved laser-based high resolution ARPES measurements have been performed on the optimally-doped $\mathrm{YBa_{2} Cu_{3} O_{7-\delta} }$ (Y123) superconductor. For the first time, we found the region from the cleaved surface that reveals clear bulk electronic properties. The intrinsic Fermi surface and band structures of Y123 are observed. The Fermi surface-dependent and momentum-dependent superconducting gap is determined which is nodeless and consistent with the d+is gap form.