Shi Xia-Qing, Cheng Fu, Chaté Hugues
Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China.
Service de Physique de l'Etat Condensé, CEA, CNRS Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France.
Phys Rev Lett. 2023 Sep 8;131(10):108301. doi: 10.1103/PhysRevLett.131.108301.
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 η not limited by the 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.
我们证明，由活性粒子制成的二维晶体可以经历极大的自发变形而不会熔化。使用主要通过成对排斥力相互作用的粒子，我们表明这种活性晶体保持长程键序和代数衰减的位置序，但指数η不受（平衡）KTHNY理论给出的1/3界限限制。我们用线性弹性理论对我们的发现进行了合理化解释，并表明存在两个明确定义的有效温度，分别量化大规模变形和键序涨落。这些现象的根源在于粒子固有轴的唯一时间持续性，因此它们应该在许多不同的情况下被观察到。
