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Effects of temperature changes on the nonequilibrium spin-glass dynamics of a strongly interacting ferromagnetic nanoparticle system (superspin glass) are studied. In contrary to atomic spin glasses, strong cooling rate effects are observed, and no evidence for temperature-chaos is found. The flip time of a magnetic moment is much longer than that of an atomic spin and hence much shorter time scales are probed within the experimental time window for a superspin glass than for an atomic spin glass. Within a real space picture the cumulative aging observed for the superspin glass can be explained considering that all investigated length scales are shorter than the temperature-chaos overlap length. The transient relaxation, observed in experiments after temperature changes, can be understood as the adjustment of thermally active droplets, which is mutatis mutandis the Kovacs effect observed in most glassy systems.
We present the experimental observation of the fluctuation-dissipation theorem (FDT) violation in an assembly of interacting magnetic nanoparticles in the low temperature superspin glass phase. The magnetic noise is measured with a two-dimension elec
We report on zero field cooled magnetization relaxation experiments on a concen- trated frozen ferrofluid exhibiting a low temperature superspin glass transition. With a method initially developed for spin glasses, we investigate the field dependence
Cryogenic rejuvenation in metallic glasses reported in Ketov et al s experiment (Nature(2015)524,200) has attracted much attention, both in experiments and numerical studies. The atomic mechanism of rejuvenation has been conjectured to be related t
We study the effect of shear on the aging dynamics of a colloidal suspension of synthetic clay particles. We find that a shear of amplitude $gamma$ reduces the relaxation time measured just after the cessation of shear by a factor $exp(-gamma/gamma_c
When a liquid is cooled below its melting temperature it usually crystallizes. However, if the quenching rate is fast enough, it is possible that the system remains in a disordered state, progressively losing its fluidity upon further cooling. When t