Electronic excitations in Bi$_2$Sr$_2$CaCu$_2$O$_8$ : Fermi surface, dispersion, and absence of bilayer splitting

TL;DR

This study uses polarization-dependent ARPES to analyze the electronic structure of Bi$_2$Sr$_2$CaCu$_2$O$_8$, revealing a single CuO$_2$ band, no bilayer splitting, and attributing spectral features to superlattice effects and many-body interactions.

Contribution

It provides detailed ARPES analysis showing the absence of bilayer splitting and clarifies the origin of spectral features in Bi$_2$Sr$_2$CaCu$_2$O$_8$.

Findings

Only one CuO$_2$ band feature observed

No evidence of bilayer splitting in spectra

The 'dip feature' arises from many-body effects

Abstract

From a detailed study, including polarization dependence, of the normal state angle-resolved photoemission spectra for Bi$_2$Sr$_2$CaCu$_2$O$_8$, we find only one CuO$_2$ band related feature. All other spectral features can be ascribed either to umklapps from the superlattice or to ``shadow bands''. Even though the dispersion of the peaks looks like band theory, the lineshape is anomalously broad and no evidence is found for bilayer splitting. We argue that the ``dip feature'' in the spectrum below $T_c$ arises not from bilayer splitting, but rather from many body effects.