On the Reconstructed Fermi Surface in the Underdoped Cuprates

TL;DR

This study uses angle-resolved photoemission to reveal that the Fermi surface in underdoped cuprates consists of fully enclosed hole pockets, not arcs, aligning with doping levels and modeled as a spin liquid.

Contribution

It provides direct evidence that the Fermi surface in underdoped cuprates is composed of hole pockets, challenging the arc interpretation and supporting a spin liquid pseudogap model.

Findings

Fermi surfaces are fully enclosed hole pockets.

Spectral weight vanishes at the anti-ferromagnetic zone boundary.

Pocket areas match the doping levels.

Abstract

The Fermi surface topologies of underdoped samples the high-Tc superconductor Bi2212 have been measured with angle resolved photoemission. By examining thermally excited states above the Fermi level, we show that the Fermi surfaces in the pseudogap phase of underdoped samples are actually composed of fully enclosed hole pockets. The spectral weight of these pockets is vanishingly small at the anti-ferromagnetic zone boundary, which creates the illusion of Fermi "arcs" in standard photoemission measurements. The area of the pockets as measured in this study is consistent with the doping level, and hence carrier density, of the samples measured. Furthermore, the shape and area of the pockets is well reproduced by a phenomenological model of the pseudogap phase as a spin liquid.