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arXiv · 2309.04212

Extreme Spontaneous Deformations of Active Crystals

Xia-qing Shi·Fu Cheng·Hugues Chaté
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Abstract

We demonstrate that two-dimensional crystals made of active particles can experience extremely large spontaneous deformations without melting. Using particles mostly interacting via pairwise repulsive forces, we show that such active crystals maintain long-range bond order and algebraically-decaying positional order, but with an exponent $\eta$ not limited by the $\tfrac{1}{3}$ bound given by the (equilibrium) KTHNY theory. We rationalize our findings using linear elastic theory and show the existence of two well-defined effective temperatures quantifying respectively large-scale deformations and bond-order fluctuations. The root of these phenomena lies in the sole time-persistence of the intrinsic axes of particles, and they should thus be observed in many different situations.

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Xia-qing Shi, Fu Cheng, Hugues Chaté. 2023-09-08. Extreme Spontaneous Deformations of Active Crystals. https://doi.org/10.1103/physrevlett.131.108301

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