Pairing from strong repulsion in triangular lattice Hubbard model

TL;DR

This paper introduces a novel pairing mechanism in doped frustrated Mott insulators, where holes form bound states mediated by magnons, potentially leading to superconductivity.

Contribution

It proposes a new three-body bound state mechanism for hole pairing driven by kinetic energy frustration in the triangular lattice Hubbard model.

Findings

Hole pairing arises from a hole-hole-magnon bound state.

Single-hole AFM polaron can bind a second hole.

Effective interaction between bound states is repulsive.

Abstract

We propose a paring mechanism between holes in the dilute limit of doped frustrated Mott insulators. Hole pairing arises from a hole-hole-magnon three-body bound state. This pairing mechanism has its roots on single-hole kinetic energy frustration, which favors antiferromagnetic (AFM) correlations around the hole. We demonstrate that the AFM polaron (hole-magnon bound state) produced by a single-hole propagating on a field-induced polarized background is strong enough to bind a a second hole. The effective interaction between these three-body bound states is repulsive, implying that this pairing mechanism is relevant for superconductivity.