Spatially Modulated Electronic Nematicity in the Three-Band Model of Cuprate Superconductors

TL;DR

This paper investigates charge instabilities and nematic order in cuprate superconductors using the three-band Emery model, revealing different types of nematic phases and their spectral and Fermi surface properties.

Contribution

It introduces a detailed analysis of spatially modulated nematic phases in the three-band model, expanding understanding beyond previous one-band models.

Findings

Identifies three types of nematic order: commensurate and two incommensurate phases.

Discovers a soft nematic mode emerging at the transition.

Discusses Fermi surface reconstructions related to nematic phases.

Abstract

Charge order in cuprate superconductors is a possible source of anomalous electronic properties in the underdoped regime. Intra-unit cell charge ordering tendencies point to electronic nematic order involving oxygen orbitals. In this context we investigate charge instabilities in the Emery model and calculate the charge susceptibility within diagrammatic perturbation theory. In this approach, the onset of charge order is signalled by a divergence of the susceptibility. Our calculations reveal three different kinds of order: a commensurate ($q=0$) nematic order, and two incommensurate nematic phases with modulation wavevectors that are either axial or oriented along the Brillouin zone diagonal. We examine the nematic phase diagram as a function of the filling, the interaction parameters, and the band structure. We also present results for the excitation spectrum near the nematic instability, and show that a soft nematic mode emerges from the particle-hole continuum at the transition. The Fermi surface reconstructions that accompany the modulated nematic phases are discussed with respect to their relevance for magneto-oscillation and photoemission measurements. The modulated nematic phases that emerge from the three-band Emery model are compared to those found previously in one-band models.