Density-wave instabilities of fractionalized Fermi liquids

TL;DR

This paper analyzes charge density wave instabilities in fractionalized Fermi liquids, explaining experimental observations in cuprates and highlighting differences from conventional antiferromagnetic metals.

Contribution

It demonstrates that the charge density wave wavevectors observed in cuprates can be explained by a fractionalized Fermi-liquid state coupled to antiferromagnetic fluctuations.

Findings

Charge density wave wavevectors match experimental data in cuprates.

Fractionalized Fermi-liquid states exhibit specific charge ordering instabilities.

Results connect pseudogap phenomena to fractionalized metallic states.

Abstract

Recent experiments in the underdoped regime of the hole-doped cuprates have found evidence for an incommensurate charge density wave state. We present an analysis of the charge ordering instabilities in a metal with antiferromagnetic correlations, where the electronic excitations are coupled to the fractionalized excitations of a quantum fluctuating antiferromagnet on the square lattice. The resulting charge density wave state emerging out of such a fractionalized Fermi-liquid (FL*) has wavevectors of the form $(\pm Q_0,0), (0,\pm Q_0)$, with a predominantly $d$-form factor, in agreement with experiments on a number of different families of the cuprates. In contrast, as previously shown, the charge density wave instability of a nearly antiferromagnetic metal with a large Fermi surface, interacting via short-range interactions, has wavevectors of the type $(\pm Q_0,\pm Q_0)$. Our results show that the observed charge density wave appears as a low-energy instability of a fractionalized metallic state linked to the proximity to an antiferromagnetic insulator, and the pseudogap regime can be described by such a metal at least over intermediate length and energy scales.