Quantum spin liquid from electron-phonon coupling.

Cai, Xun; Han, Zhaoyu; Li, Zi-Xiang; Kivelson, Steven A; Yao, Hong · Proc Natl Acad Sci U S A · 2025

basic_science · Level V

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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 "nonengineered" 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 nonengineered electron-phonon model. Specifically, we investigate the ground-state phase diagram of the bond Su-Schrieffer-Heeger model on a 2D triangular lattice at (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 promising routes for finding QSLs in realistic materials and high-<i>T</i><sub><i>c</i></sub> superconductivity by lightly doping them.