Shadow bands in single-layered Bi2 Sr2 Cu O6+δ studied by angle-resolved photoemission spectroscopy

Abstract

We have performed systematic angle-resolved photoemission spectroscopy (ARPES) on single-layered cuprate superconductor Bi2 Sr2 Cu O6+δ to elucidate the origin of shadow band. We found that the shadow band is exactly the c (2×2) 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 La1.85 Sr0.15 Cu O4 also clarified the existence of the c (2×2) 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. © 2006 The American Physical Society.