Understanding the origin of the shadow bands of Bi-based superconductors with angle resolved photoemission

Abstract

Angle resolved photoemission spectroscopy (ARPES) has been used to investigate the shadow bands (SB) present at the Fermi surface (FS) of bismuth based superconductors. Bi 2Sr 2CaCu 2O 8+ δ (Bi-2212) single crystals and Bi 2Sr 2CuO 6+ δ (Bi-2201) thin films have been studied by momentum distribution curves (MDCs) along the ΓY high symmetry direction in two different Brillouin zones (BZ). The results show the ratio shadow bands/main band (SB/MB) to be constant as a function of both the doping level and the number of CuO 2 planes, which discards the antiferromagnetic (AF) scenario to explain their origin. On the other hand, the SB and the main bands (MB) have different initial state symmetry, which implies that the orthorhombicity exhibited by these materials cannot be responsible for their emergence at the FS. An interpretation on the basis of a c(2 × 2) surface reconstruction, recently observed by LEED, becomes be only plausible explanation compatible with all experimental data.