Breaking Of Ergodicity In A Canonical Spin System

Breaking of ergodicity occurs when the phase space of an anisotropic spin system is disconnected. The related 11phase'' separation produces a power-law divergence of the recurrence time within one disconnected portion (demagnetization time) at some critical energy. Such average time can be also evaluated for a system in contact with a thermal bath and found to diverge at low temperature even for few particle systems.