Origin of the Peak-Dip-Hump Line Shape in the Superconducting-State $(\pi ,0)$ Photoemission Spectra of ${\mathrm{B}\mathrm{i}}_2{\mathrm{S}\mathrm{r}}_2{\mathrm{C}\mathrm{a}\mathrm{C}\mathrm{u}}_2{\mathrm{O}}_8$

From detailed high-resolution measurements of the photon energy dependence of the $(\pi ,0)$ superconducting-state photoemission spectrum of the bilayer Bi high-temperature superconductors, we show that the famous peak-dip-hump line shape is dominated by a superposition of spectral features originating from different electronic states which reside at different binding energies, but are each describable by essentially identical single-particle spectral functions. The previously identified bilayer-split ${\mathrm{C}\mathrm{u}\mathrm{O}}_2$ bands are the culprit: with the ”superconducting” peak being due to the antibonding band, while the hump is mainly formed by its bonding bilayer-split counterpart.

Figure 1

Fermi surface maps of pure Bi2212 (left panel) and Pb-Bi2212 (right panel) measured at room temperature.

Figure 2

The $(\pi ,0)$ photoemission spectra from the superconducting state of an overdoped (69 K) sample for different excitation energies: the black lines show the experimental data and the colored lines represent the results of a fitting procedure described in the text.

Figure 3

The intensity prefactors $M_a$, $M_b$, and $M_c$ as functions of excitation energy for the two-feature (upper panel) and three-feature (lower panel) fitting procedure.