Shadow bands in single-layered Bi_2Sr_2CuO_6 studied by angle-resolved photoemission spectroscopy

TL;DR

This study uses ARPES to investigate shadow bands in single-layered cuprates, revealing their structural origin linked to surface orthorhombic distortion, rather than magnetic correlations, across different compounds and doping levels.

Contribution

It demonstrates that shadow bands are due to surface structural distortion, not magnetic effects, and are present in multiple cuprate materials.

Findings

Shadow band is a c(2x2) replica of the main band.

Shadow band intensity is unaffected by doping, temperature, or substitution.

Shadow bands are linked to surface orthorhombic distortion.

Abstract

We have performed systematic angle-resolved photoemission spectroscopy (ARPES) on single-layered cuprate superconductor Bi2Sr2CuO6 to elucidate the origin of shadow band. We found that the shadow band is exactly the c(2x2) replica of the main band irrespective of the carrier concentration and its intensity is invariable with respect to temperature, doping, and substitution constituents of block layers. This result rules out the possibility of antiferromagnetic correlation and supports the structural origin of shadow band. ARPES experiments on optimally doped La1.85Sr0.15CuO4 also clarified the existence of the c(2x2) shadow band, demonstrating that the shadow band is not a unique feature of Bi-based cuprates. We conclude that the shadow band is related to the orthorhombic distortion at the crystal surface.