Magnetic properties of nanocomposite Fe–Pt films with Fe concentration higher than 50 at % have been investigated in this study. Fe/Pt multilayers were produced by sputtering and magnetic hardening was observed after heat treatment including rapid annealing. The final nanocomposite films consisted of the hard face-centered tetragonal FePt phase and a soft face-centered-cubic phase. The maximum energy products of the optimally processed samples exceeded 40 MGOe. Evidence for exchange coupling of the hard and soft phases was found.

Polymer chains form lamellar structures during crystallization which display a memory of thermal history. Using molecular dynamics simulations and primitive path analysis, we show a direct dependence of both density and crystalline stem length on the local entanglement length. The slow relaxation of the entanglement state after a change of external conditions can directly explain the role of thermal history for polymer crystallization, in particular memory effects. The analysis of the local entanglement state can be used to predict the occurrence of nucleation events. Our results present a fresh insight of the nonequilibrium properties of polymer crystals which might be identified as "frozen topology" of polymer melts.

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Using molecular dynamics simulations and primitive path analysis, we show that hot entangled polymer melts can crystallize faster with higher crystallinities and larger crystalline stem lengths, as compared to cold melts under rapid quenching conditions or during cold-crystallization. This counterintuitive phenomenon similar to the so-called Mpemba effect observed for water can be explained by the temperature dependence of entanglements. Our results demonstrate the key role of the entanglement state for crystallization properties and provide a new approach to understand the role of thermal history and to the open question of thickness selection in polymer crystallization.

Large scale and long time molecular dynamics simulations and primitive path analysis are used to investigate the disentanglement of long linear polymer chains during their crystallization from the melt state. In general, two competitive processes, a slow decrease of average entanglement length during cooling caused by stiffening of chains and a strong increase during crystallization, can be observed. In both homogeneous and heterogeneous nucleation, disentanglement occurs via forming folds from locally unentangled segments and continues in postcrystallization processes (slow reorganization), in particular, during annealing. Re-entanglement processes after melting are slow and can lead to memory effects in heating–recooling protocols such as self-seeding.