Stabilizing Role of Mesoscopic Fluctuations in Spin Systems

The occurrence of mesoscopic fluctuations in statistical systems implies, from the point of view of dynamical theory, the existence of local instabilities. However, the presence of such fluctuations can make a system, as a whole, more stable from the thermodynamic point of view. Thus, in many cases, a local dynamic instability is a requisite for the global thermodynamic stability. This idea is illustrated by several spin models.