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17.6.26 14:30 s.t. - Seminarroom 25.32 O2.51
Smarajit Karmakar: „Strong Dynamic Fluctuations in Active Crystals and Glasses”
Tata Institute of Fundamental Research, Hyderabad, India
Activity-driven glassy dynamics are ubiquitous in collective cell migration, intracellular transport, and dynamics in bacterial and ant colonies, as well as artificially driven synthetic systems such as vibrated granular materials, etc. Active glasses are hitherto assumed to be qualitatively similar to their equilibrium counterparts at a suitably defined effective temperature. Using large-scale simulations, we show that an active glass is qualitatively different from an equilibrium glassy system. Although the relaxation dynamics can resemble those of an equilibrium system at an appropriate effective temperature, the effects of activity on dynamic heterogeneity (DH), which has emerged as a cornerstone of glassy dynamics, are nontrivial and complex. In particular, active glasses show dramatic growth of DH, and systems with similar relaxation times can have widely varying DH. In particular, we demonstrate a dramatic increase in the correlation length in these systems with increasing activity, which is very different from that in passive glasses. I will touch upon our proposal to measure the strong growth of dynamic heterogeneity and its associated length scale in these systems using a rod-like probe particle. Finally, with time permitting, I will discuss the effect of these active fluctuations on the stability of active solids, showing that Mermin-Wagner-like long-wavelength fluctuations are enhanced by active particles, leading to faster-than-logarithmic divergence of Debye-Waller factors with system size in two dimensions and logarithmic divergence in three dimensions.
References
- Dynamic heterogeneity in active glass-forming liquids is qualitatively different compared to its equilibrium behaviour - K Paul, A Mutneja, SK Nandi, Smarajit Karmakar, PNAS 120 (34) e2217073120 (2023).
- Method to probe the pronounced growth of correlation lengths in active glass-forming liquids using an elongated probe, A. Mutneja, Smarajit Karmakar, Phys. Rev. E Lett. 108(2) L022601 (2023).
- Enhanced Long Wavelength Mermin-Wagner-Hohenberg Fluctuations in Active Crystals and Glasses - S Dey, A Bhattacharya, S Karmakar, Nature Communications 16 (1), 5498 (2025).
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