Aging phenomena of magnetization in a hierarchical diffusion model

The magnetization is introduced to a hierarchical diffusion model and a rel ation between the response function and the correlation function is derived to evaluate the zero-field-cooled magnetization (ZFCM) and the thermoreman ent magnetization (TRM). It is found that if the correlation of distributio n of magnetization (CDM) is weak, the behaviors of ZFCM and TRM are governe d by the distribution of the barrier energy. The aging is observed in this case. On the other hand, these behaviors are governed by the strength of CD M if it is strong enough, and the aging is not observed.