Myriad phases of the Checkerboard Hubbard Model

TL;DR

This paper maps out the complex zero-temperature phase diagram of the checkerboard Hubbard model, revealing at least 16 phases, including a novel d-wave Mott insulator and various superconducting and Fermi liquid states, depending on doping and interaction strength.

Contribution

It provides a detailed phase diagram of the checkerboard Hubbard model in a solvable limit, identifying new phases and transitions not previously characterized.

Findings

Identification of at least 16 distinct phases.

Discovery of a novel d-wave Mott insulator at zero doping.

Doping induces transitions to superconducting and Fermi liquid states.

Abstract

The zero temperature phase diagram of the checkerboard Hubbard model is obtained in the solvable limit in which it consists of weakly coupled square plaquettes. As a function of the on-site Coulomb repulsion U and the density of holes per site, x, we demonstrate the existence of at least 16 distinct phases. For instance, at zero doping, the ground state is a novel d-wave Mott insulator (d-Mott), which is not adiabatically continuable to a band insulator; by doping the d-Mott state with holes, depending on the magnitude of U, it gives way to a d-wave superconducting state, a two-flavor spin-1/2 Fermi liquid (FL), or a spin-3/2 FL.