High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi2Sr2CaCu2Ox

TL;DR

This study used scanning tunneling spectroscopy to reveal stripe structures and vortex core states in Bi2Sr2CaCu2Ox, showing how local electronic patterns influence vortex behavior and quasiparticle states.

Contribution

It provides new insights into the spatial structure of vortex cores and their relation to short-range electronic order in high-temperature superconductors.

Findings

Vortex cores exhibit stripe structures aligned with Cu-O bonds.

Vortex core states appear as symmetric peaks unaffected by local gap variations.

Mazelike patterns coexist with superconductivity and influence vortex core orientation.

Abstract

We studied electronic states in vortex cores of slightly overdoped Bi2Sr2CaCu2Ox by scanning tunneling spectroscopy. We have found that they have stripe structures with a 4a0 width extending along the Cu-O bond directions. Vortex core states are observed as two peaks at particle-hole symmetric positions in the energy gap. Along a stripe, the peak positions of vortex core states are constant and not influenced by the spatial variation of the energy gap \Delta. Outer stripes have a larger energy than inner stripes. A mazelike pattern in the electronic states at E = +-\Delta has been observed all over the surface both inside and outside the vortex core. The orientation of stripes of vortex core states was found to be related to the mazelike pattern in the vortex core region. A short-range order of the mazelike pattern spatially coexists with the superconductivity and locally breaks the symmetry of the two Cu-O bond directions. We propose that the vortex core bound states are formed by Bogoliubov quasiparticles owing to the depairing of Cooper pairs and have a local C2 symmetry influenced by the short-range order of the mazelike pattern.