Non-equilibrium Muon Dynamics Imitating Fractional Spin Excitations in a Quantum Spin Chain
Researchers used muon spin rotation ($ ext{µSR}$) to study AgCuVO$_4$, a spin-1/2 chain compound, looking for evidence of fractional spin excitations. They found that the field-resilient muon polarization decay is not due to intrinsic sporadic spin fluctuations but instead arises from non-equilibrium muon dynamics, specifically a two-state model where the muon randomly hops between two nearby sites.