Quantum spin liquid from electron-phonon coupling

TL;DR

This paper demonstrates that a quantum spin liquid (QSL) can emerge in a realistic electron-phonon model on a 2D lattice, providing new insights into material design and high-temperature superconductivity.

Contribution

The study shows, through exact quantum Monte Carlo simulations, that a QSL phase exists in a non-engineered electron-phonon model, specifically the 2D bond SSH model on a triangular lattice.

Findings

QSL phase is fully gapped and exhibits no symmetry-breaking order.

The QSL supports deconfined fractionalized holon excitations.

Results suggest new routes for discovering QSLs and high-$T_c$ superconductivity in real materials.

Abstract

A quantum spin liquid (QSL) is an exotic insulating phase with emergent gauge fields and fractionalized excitations. However, the unambiguous demonstration of the existence of a QSL in a "non-engineered" microscopic model (or in any material) remains challenging. Here, using numerically-exact sign-problem-free quantum Monte Carlo simulations, we show that a QSL arises in a non-engineered electron-phonon model. Specifically, we investigate the ground-state phase diagram of the bond Su-Schrieffer-Heeger (SSH) model on a 2D triangular lattice at half filling (one electron per site) which we show includes a QSL phase which is fully gapped, exhibits no symmetry-breaking order, and supports deconfined fractionalized holon excitations. This suggests new routes for finding QSLs in realistic materials and high-$T_c$ superconductivity by lightly doping them.