Fermi surface evolution in underdoped cuprates

TL;DR

This paper models the evolution of the Fermi surface in underdoped cuprates, showing a transition from large to small pockets as coupling strength increases, aligning with experimental observations.

Contribution

It introduces a theoretical framework for Fermi surface evolution in cuprates, connecting coupling strength to Fermi surface topology changes and quasiparticle residue variations.

Findings

Fermi surface transitions from large to small pockets with increasing coupling

Intermediate coupling features coexistence of large Fermi surface and pockets

Results align with photoemission experiments in YBCO and Bi2212

Abstract

We consider a two-dimensional Fermi liquid coupled to low-energy commensurate spin fluctuations. At small coupling, the hole Fermi surface is large and centered around $(\pi,\pi)$. We show that as the coupling increases, the shape of the Fermi surface undergoes a substantial evolution, and at strong coupling, the hole Fermi surface consists of small pockets centered at $(\pm \pi/2, \pm \pi/2)$. At intermediate couplings, there exists a large hole Fermi surface centered at $(\pi,\pi)$ as well as four hole pockets, but the quasiparticle residue is small everywhere except for the pieces of the pockets which face the $\Gamma$ point. The relevance of these results to recent photoemission experiments in $YBCO$ and $Bi2212$ systems, and their relation to the Luttinger theorem are discussed.