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

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 Q=(π,π) 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 , Nat. Phys. 18, 511 (2022)1745-247310.1038/s41567-022-01529-8], 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.