Unambiguous connection between the Fermi surface topology and the pseudogap in Bi$_{2}$Sr$_2$CaCu$_2$O$_{8+d}$

TL;DR

This study demonstrates that the pseudogap in Bi$_{2}$Sr$_2$CaCu$_2$O$_{8+d}$ is directly linked to the Fermi surface topology, disappearing when the Fermi surface changes from hole-like to electron-like at a critical doping.

Contribution

It provides direct experimental evidence connecting the pseudogap's existence to the Fermi surface topology in a high-temperature superconductor.

Findings

Pseudogap vanishes above critical doping p_c=0.22.

Fermi surface topology changes from hole-like to electron-like at p_c.

Pseudogap depends on Fermi surface topology, constraining theoretical models.

Abstract

We study the behavior of the pseudogap in overdoped Bi$_{2}$Sr$_2$CaCu$_2$O$_{8+d}$ by electronic Raman scattering (ERS) and angle-resolved photoemission spectroscopy (ARPES) on the same single crystals. Using both techniques we find that, unlike the superconducting gap, the pseudogap related to the anti-bonding band vanishes above the critical doping p$_c$ = 0.22. Concomitantly, we show from ARPES measurements that the Fermi surface of the anti-bonding band is hole-like below pc and becomes electron-like above p$_c$. This reveals that the appearance of the pseudogap depends on the Fermi surface topology in Bi$_{2}$Sr$_2$CaCu$_2$O$_{8+d}$ , and more generally, puts strong constraint on theories of the pseudogap phase.