Strong pair-density-wave fluctuations in an exactly solvable doped Mott insulator

TL;DR

This paper demonstrates the emergence of strong pair-density-wave fluctuations and superconducting instability in an exactly solvable doped Mott insulator model, providing insights into pseudogap phenomena relevant to cuprate superconductors.

Contribution

It reveals the presence of PDW fluctuations and superconductivity in the HK model with pairing, connecting Mott physics to high-temperature superconductor behavior.

Findings

Strong PDW fluctuations at finite temperature and low doping.

Superconducting instability over a wide interaction and doping range.

Potential relevance to cuprate pseudogap physics.

Abstract

We investigate the Hatsugai-Kohmoto (HK) model on a square lattice, which describes both a Mott insulator at half-filling and a non-Fermi liquid phase on doping. Through the solution of this exactly solvable model with the inclusion of pairing interactions, we demonstrate the emergence of strong pair-density-wave (PDW) fluctuations associated with center-of-mass momentum $\mathbf{Q}=(\pi,\pi)$ at finite temperatures for low dopings up to a critical doping and intermediate $U$ interaction. Furthermore, we also confirm that a superconducting instability appears in the model within a wide regime of interaction $U$ and doping parameter $x$. In view of the fact that it has been recently put forward that the metal-insulator transition of the HK model belongs to the same universality class as the Mott transition of the paradigmatic Hubbard model [Huang \emph{et al.}, Nat. Phys. \textbf{18}, 511 (2022)], our work may thus shed light on an interesting scenario regarding the emergence of a fluctuating PDW phase on doping a Mott insulator, which has been argued to be relevant for understanding the physics of the cuprate superconductors in the underdoped regime.