Dynamical Time-Reversal Symmetry Breaking and Photo-Induced Chiral Spin Liquids in Frustrated Mott Insulators

TL;DR

This paper demonstrates that circularly-polarized light can induce a chiral spin liquid phase in frustrated Mott insulators, providing a new method to realize and study topological quantum spin liquids dynamically.

Contribution

It introduces a Floquet-driven approach to generate a chiral spin liquid in a Kagome Mott insulator by breaking time-reversal symmetry with light, while maintaining SU(2) symmetry.

Findings

Photo-induced chiral spin liquid near equilibrium state

Effective Floquet spin model captures driven dynamics

Suppressed heating allows stable phase realization

Abstract

The search for quantum spin liquids in frustrated quantum magnets recently has enjoyed a surge of interest, with various candidate materials under intense scrutiny. However, an experimental confirmation of a gapped topological spin liquid remains an open question. Here, we show that circularly-polarized light can provide a novel knob to drive frustrated Mott insulators into a chiral spin liquid (CSL), realizing an elusive quantum spin liquid with topological order. We find that the dynamics of a driven Kagome Mott insulator is well-captured by an effective Floquet spin model, with heating strongly suppressed, inducing a scalar spin chirality $S_i \cdot (S_j \times S_k)$ term which dynamically breaks time-reversal while preserving SU(2) spin symmetry. We fingerprint the transient phase diagram and find a stable photo-induced CSL near the equilibrium state. The results presented suggest employing dynamical symmetry breaking to engineer quantum spin liquids and access elusive phase transitions that are not readily accessible in equilibrium.