Quantum spin liquids from electron-phonon coupling: a numerically-exact quantum Monte Carlo study

Quantum spin liquids (QSL) are exotic quantum phases of matter that support fractionalized excitations and also provide a route to realize superconductivity (SC) after doping. Here we explore whether electron-phonon coupling (EPC) could provide a new mechanism of realizing QSL. Indeed, by employing the numerically-exact quantum Monte Carlo method, we show that Su-Schrieffer-Heeger (SSH) electron-phonon coupling on the triangular lattice at half filling can induce a gapped QSL phase. The half-filled SSH electron-phonon model features the competition between phonon-mediated SC at weak electron-phonon coupling and valence bond solid (VBS) phase at strong electron-phonon coupling. We find that QSL phase emerges between SC and VBS. Our finding sheds new light on microscopic mechanism of QSL in correlated quantum materials.