Statistical-mechanical formalism for spin-glasses

A consistent description of the spin-glass transition and the spin-glass phase is possible within the context of equilibrium statistical mechanics. This conclusion is based on two arguments. First, every equilibrium state may be decomposed uniquely into its ergodic components, which represent the pure thermodynamic phases. Second, all the ergodic components have the same free energy. A detailed analysis of the ensuing conceptual structure is given and its agreement with experiments on field-cooled spin-glasses is pointed out.