The change of Fermi surface topology in Bi2Sr2CaCu2O8 with doping

TL;DR

This study uses ARPES data to reveal a doping-dependent topological change in the Fermi surface of Bi2Sr2CaCu2O8, showing a transition from hole-like to electron-like in the antibonding sheet, which is common among hole-doped superconductors.

Contribution

It provides direct experimental evidence of Fermi surface topology change with doping in Bi2Sr2CaCu2O8, clarifying its relation to superconductivity and comparing it with other cuprates.

Findings

Fermi surface changes from hole-like to electron-like with doping.

The topology change occurs at a doping level not affecting Tc.

Similar Fermi surface topology changes are observed in other hole-doped cuprates.

Abstract

We report the observation of a change in Fermi surface topology of Bi2Sr2CaCu2O8 with doping. By collecting high statistics ARPES data from moderately and highly overdoped samples and dividing the data by the Fermi function, we answer a long standing question about the Fermi surface shape of Bi2Sr2CaCu2O8 close to the (pi,0) point. For moderately overdoped samples (Tc=80K) we find that both the bonding and antibonding sheets of the Fermi surface are hole-like. However for a doping level corresponding to Tc=55K we find that the antibonding sheet becomes electron-like. This change does not directly affect the critical temperature and therefore the superconductivity. However, since similar observations of the change of the topology of the Fermi surface were observed in LSCO and Bi2Sr2Cu2O6, it appears to be a generic feature of hole-doped superconductors. Because of bilayer splitting, though, this doping value is considerably lower than that for the single layer materials, which again argues that it is unrelated to Tc.