  The nano-particle systems under theoretically and experimentally
investigation because of the potential applications in the nano-technology such
as drug delivery, ferrofluids mechanics, magnetic data storage, sensors,
magnetic resonance imaging, and cancer therapy. Recently, it is reported that
interacting nano-particles behave as spin-glasses and experimentally show that
the relaxation of these systems obeys stretched exponential i.e., KWW
relaxation. Therefore, in this study, considering the interacting nano-particle
systems we model the relaxation and investigate frequency and temperature
behaviour depends on slow relaxation by using a simple operator formalism. We
show that relaxation deviates from Debye and obeys to KWW in the presence of
the memory effects in the system. Furthermore, we obtain the frequency and
temperature behaviour depend on KWW relaxation. We conclude that the obtained
results are consistent with experimental results and the simple model,
presented here, is very useful and pedagogical to discuss the slow relaxation
of the interacting nano-particles.
