A path to superconductivity via strong short-range repulsion in a spin-polarized band

TL;DR

This paper predicts that strong short-range repulsion in spin-polarized electrons on a 2D triangular lattice can lead to f-wave superconductivity, with pairing emerging from subleading interactions due to symmetry constraints.

Contribution

It introduces a mechanism where symmetry suppresses first-order repulsion, allowing higher-order processes to induce f-wave pairing in a strongly correlated system.

Findings

f-wave pairing arises in spin-polarized electrons on a triangular lattice

Critical temperature estimated at about 1% of bandwidth

Third-order calculations confirm the robustness of pairing mechanism

Abstract

We predict that the spin-polarized electrons in a two-dimensional triangular lattice with strong electron-electron repulsion gives rise to f-wave pairing. The key point is that the first-order interaction, which is usually pair-breaking, vanishes or nearly vanishes in certain f-wave channels due to symmetry constraints. As a result, these f-wave pairing channels are governed by the subleading-order processes which enable pairing when the perturbation theory is controlled. We illustrate this using the Hubbard model on the triangular lattice with on-site and nearest-neighbor repulsion, where we find a $T_c\sim 1\% $ of electron's bandwidth. For a general screened interaction, the same idea works asymptotically, but a third-order calculation is needed to fully determine the strength of f-wave pairing.