Electron pairing induced by repulsive interactions in tunable one-dimensional platforms

TL;DR

This paper proposes a tunable one-dimensional system where repulsive electron interactions can lead to bound pair formation, with potential implications for understanding unconventional superconductivity in low-dimensional materials.

Contribution

It introduces a scheme using a coupled quantum wire and a strongly-correlated fermionic system to induce electron pairing from repulsive interactions, highlighting controllable phase transitions.

Findings

Bound electron pairs can form despite repulsive interactions.

Superconducting correlations dominate in a specific parameter regime.

Phase diagram includes decoupled, paired, and trion phases.

Abstract

We present a scheme comprised of a one-dimensional system with repulsive interactions, in which the formation of bound pairs can take place in an easily tunable fashion.By capacitively coupling a primary electronic quantum wire of interest to a secondary strongly-correlated fermionic system, the intrinsic electron-electron repulsion may be overcome, promoting the formation of bound electron pairs in the primary wire. The intrinsic repulsive interactions tend to favor the formation of charge density waves of these pairs, yet we find that superconducting correlations are dominant in a limited parameter regime. Our analysis show that the paired phase is stabilized in an intermediate region of phase space, encompassed by two additional phases: a decoupled phase, where the primary wire remains gapless, and a trion phase, where a primary electron pair binds a charge carrier from the secondary system. Tuning the strength of the primary-secondary interaction, as well as the chemical potential of the secondary system, one can control the different phase transitions. Our approach takes into account the interactions among the secondary degrees of freedom, and strongly relies on their highly correlated nature. Extension of our proposal to two dimensions is discussed, and the conditions for a long-range superconducting order from repulsion only are found. Our physical description, given by a simple model with a minimal amount of ingredients, may help to shed some light on pairing mechanism in various low-dimensional strongly correlated materials.