Charge-fluctuations in lightly hole-doped cuprates: effect of vertex corrections

TL;DR

This paper investigates how charge fluctuations and ordering develop in lightly hole-doped cuprates by including vertex corrections in the Hubbard model, revealing momentum-dependent suppression and zero-wavevector charge instability.

Contribution

It introduces a detailed calculation of the charge response with frequency-dependent vertex corrections, showing the emergence of charge order at zero wave-vector in lightly doped cuprates.

Findings

Charge fluctuations at hot-spot wave vectors are suppressed faster near the Mott phase.

Charge susceptibility becomes highly momentum-dependent due to vertex corrections.

Charge order occurs only at zero wave-vector in the lightly doped Mott phase.

Abstract

Identification of the electronic state that appears upon doping a Mott insulator is important to understand the physics of cuprate high-temperature superconductors. Recent scanning tunneling microscopy of cuprates provides evidence that a charge-ordered state emerges before the superconducting state upon doping the parent compound. We study this phenomenon by computing the charge response function of the Hubbard model including frequency-dependent local vertex corrections that satisfy the compressibility sum-rule. We find that upon approaching the Mott phase from the overdoped side, the charge fluctuations at wave vectors connecting hot spots are suppressed much faster than at the other wave-vectors. It leads to a momentum dependence of the dressed charge susceptibility that is very different from either the bare susceptibility or from the susceptibility obtained from the random phase approximation. We also find that the paramagnetic lightly hole-doped Mott phase at finite-temperature is unstable to charge ordering only at zero wave-vector, confirming the results previously obtained from the compressibility. Charge order is driven by the frequency-dependent scattering processes that induce an attractive particle-hole interaction at large interaction strength and small doping.