Effect of Disorder on Charge Density Wave and Superconducting Order in the Half-Filled Attractive Hubbard Model

TL;DR

This paper investigates how disorder affects the coexistence of charge density wave and superconducting order in the half-filled attractive Hubbard model, showing superconductivity persists longer than charge order under randomness.

Contribution

It introduces a detailed analysis of disorder effects on competing orders in the Hubbard model and tests a strong coupling mapping to a random-field Heisenberg model.

Findings

Superconducting order persists up to a critical disorder level.

Charge order is immediately suppressed by disorder.

The strong coupling picture maps the system onto a Heisenberg model in a random magnetic field.

Abstract

The half-filled attractive Hubbard model exhibits simultaneous charge density wave and superconducting order in its ground state. In this paper we explore the effect of disorder in the site energies on this degeneracy. We find that superconducting order survives randomness out to a critical amount of disorder, but charge ordering is immediately reduced. We explore the validity of a strong coupling picture which maps the system onto a Heisenberg model in a random magnetic field.