Not all doped Mott insulators have a pseudogap: key role of van Hove singularities

TL;DR

This study reveals that not all doped Mott insulators exhibit a pseudogap, emphasizing the critical influence of van Hove singularities and band parameters on the pseudogap phenomenon in high-$T_c$ cuprates.

Contribution

It demonstrates that the pseudogap's presence in doped Mott insulators depends on band structure details, challenging the assumption that it always derives from Mottness.

Findings

Pseudogap absence in some doped Mott insulators.

Van Hove singularities critically influence pseudogap formation.

A simple equation describes the evolution of electronic scattering features.

Abstract

The Mott insulating phase of the parent compounds is frequently taken as starting point for the underdoped high-$T_c$ cuprate superconductors. In particular, the pseudogap state is often considered as deriving from the Mott insulator. In this work, we systematically investigate different weakly-doped Mott insulators on the square and triangular lattice to clarify the relationship between the pseudogap and Mottness. We show that doping a two-dimensional Mott insulator does not necessarily lead to a pseudogap phase. Despite its inherent strong-coupling nature, we find that the existence or absence of a pseudogap depends sensitively on non-interacting band parameters and identify the crucial role played by the van Hove singularities of the system. Motivated by a SU(2) gauge theory for the pseudogap state, we propose and verify numerically a simple equation that governs the evolution of characteristic features in the electronic scattering rate.