Broken Ergodicity in Classically Chaotic Spin Systems

A one dimensional classically chaotic spin chain with asymmetric coupling and two different inter-spin interactions, nearest neighbors and all-to-all, has been considered. Depending on the interaction range, dynamical properties such as ergodicity and chaoticity are very different. Indeed, even in the presence of chaoticity, the model displays a lack of ergodicity only in presence of all to all interaction and below an energy threshold, that persists in the thermodynamical limit. The energy threshold can be found analytically and results can be generalized for a generic XY model with asymmetric coupling.