Antiferromagnetism and Tightly Bound Cooper Pairs Induced by Kinetic Frustration

TL;DR

This paper shows that kinetic frustration in a square-lattice Hubbard model enables the coexistence of antiferromagnetism and superconductivity by promoting a novel pairing mechanism involving holes on opposite sublattices.

Contribution

It introduces a new pairing mechanism driven by kinetic frustration, demonstrating coexistence of antiferromagnetism and superconductivity in a minimal model.

Findings

Kinetic frustration facilitates hole pairing via spin singlet formation.

Holes on opposite sublattices behave as if carrying opposite effective charges.

The model supports a robust $d$-wave superconducting state within an antiferromagnetic background.

Abstract

Antiferromagnetism and superconductivity are often viewed as competing orders in correlated electron systems. Here, we demonstrate that kinetic frustration in hole motion facilitates their coexistence within the square-lattice repulsive Hubbard model. Combining exact analytical solutions on tailored geometries with large-scale numerical simulations, we reveal a robust pairing mechanism: holes on opposite sublattices behave as if they carry opposite effective charges due to spin singlet formation from kinetic frustration. This emergent property suppresses phase separation and fosters a coherent $d$-wave superconducting channel embedded within a long-range antiferromagnetic background. Our findings establish a minimal yet broadly applicable framework for stabilizing strong-coupling superconductivity in doped Mott insulators.