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A Comment on "Memory Effects in an Interacting Magnetic Nanoparticle System"
Recently, Sun et al reported that striking memory effects had been clearly
observed in their new experiments on an interacting nanoparticle system [1].
They claimed that the phenomena evidenced the existence of a spin-glass-like
phase and supported the hierarchical model. No doubt that a particle system may
display spin-glass-like behaviors [2]. However, in our opinion, the experiments
in Ref. [1] cannot evidence the existence of spin-glass-like phase at all. We
will demonstrate below that all the phenomena in Ref. [1] can be observed in a
non-interacting particle system with a size distribution. Numerical simulations
of our experiments also display the same features.Comment: A comment on "Phys. Rev. Lett. 91, 167206
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