Dynamic specific heat of spin glasses: Studies of a spin cluster

An internal energy response to small temperature oscillations is used to define the dynamic specific heat c(ω). The properties of c(ω) are analyzed for a six-site cluster of Ising spins within the framework of the Glauber model. The cluster has three local energy minima and thus three diverging relaxation times in the time evolution of magnetization and two such times in the evolution of energy. The dynamic specific heat allows the study of the relaxational spectrum of the energy but, as opposed to the dynamic spin susceptibility, it is not affected by the longest relaxing mode. For a uniform ferromagnet c(ω) is sensitive only to rapidly relaxing processes.