Abstract: In heterogeneous materials, such as in biological cells, porous media or ionic conductors, anomalous diffusion is observed, i. e. the mean-squared displacement (MSD) of a tracer particle grows sub-diffusively over long periods of time. A paradigm for modeling of transport in heterogeneous media is the Lorentz Model, in which a single mobile particle moves in a static matrix built of overlapping hard disk obstacles. There, anomalous diffusion is the signature of a universal localization transition caused by the percolation of the matrix. In experiments and simulations, a wide range of exponents have been reported, and it remains unclear if those exponents represent transient behavior, or whether they can be connected to a universal behavior. We generalized the Lorentz Model in molecular dynamics simulations by introducing interacting tracer particles and soft interactions and performed experiments of a colloidal Lorentz Model. We showed that due to the soft interactions the localization transition becomes rounded and that the universality of the dynamics breaks down.

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