Dissipative Structure in Driven Spin-Phonon Systems.

Dissipative structures, self-organized patterns stabilized by driving and dissipation, are well known in fluids, chemistry, and optics, yet their realization in crystalline solids remains largely unexplored. In solids, nonlinear phononics has emerged as a powerful approach to control lattice and electronic degrees of freedom, but its influence has been mostly limited to reshaping the equilibrium energy landscape, while dissipation has often been treated as a secondary effect. Here we ask whether dissipation itself can be leveraged to create genuine non-equilibrium phases of matter in nonlinear phononics. We address this question by studying a driven spin-phonon system under circularly polarized light, where the interplay of nonlinearity, driving, and dissipation produces fractional frequency locking in the phonon angular momentum—a temporal dissipative structure that breaks discrete time-translation symmetry. Phase diagrams and stability analyses reveal the regimes where dissipation plays a constructive role in sustaining such steady states. These findings establish a pathway toward light-driven, dissipation-stabilized phases in spin-phonon materials such as CeF3.