Klongvessa Natsuda, Ybert Christophe, Cottin-Bizonne Cécile, Kawasaki Takeshi, Leocmach Mathieu
School of Physics, Center of Excellence in Advanced Functional Materials, Institute of Science, Suranaree University of Technology, 3000 Nakhon Ratchasima, Thailand.
Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France.
J Chem Phys. 2022 Apr 21;156(15):154509. doi: 10.1063/5.0087578.
Among amorphous states, glass is defined by relaxation times longer than the observation time. This nonergodic nature makes the understanding of glassy systems an involved topic, with complex aging effects or responses to further out-of-equilibrium external drivings. In this respect, active glasses made of self-propelled particles have recently emerged as a stimulating systems, which broadens and challenges our current understanding of glasses by considering novel internal out-of-equilibrium degrees of freedom. In previous experimental studies we have shown that in the ergodicity broken phase, the dynamics of dense passive particles first slows down as particles are made slightly active, before speeding up at larger activity. Here, we show that this nonmonotonic behavior also emerges in simulations of soft active Brownian particles and explore its cause. We refute that the deadlock by emergence of active directionality model we proposed earlier describes our data. However, we demonstrate that the nonmonotonic response is due to activity enhanced aging and thus confirm the link with ergodicity breaking. Beyond self-propelled systems, our results suggest that aging in active glasses is not fully understood.
在非晶态中，玻璃态的定义是弛豫时间长于观测时间。这种非遍历性使得对玻璃态系统的理解成为一个复杂的话题，涉及复杂的老化效应或对进一步非平衡外部驱动的响应。在这方面，由自驱动粒子构成的活性玻璃最近作为一种令人兴奋的系统出现了，它通过考虑新的内部非平衡自由度拓宽并挑战了我们目前对玻璃态的理解。在先前的实验研究中我们已经表明，在遍历性破缺阶段，随着粒子变得稍有活性，密集的被动粒子的动力学首先会减慢，然后在活性更大时加速。在这里，我们表明这种非单调行为也出现在软活性布朗粒子的模拟中，并探究其原因。我们驳斥了我们之前提出的活性方向性模型导致的僵局能够描述我们的数据这一观点。然而，我们证明这种非单调响应是由于活性增强的老化，从而证实了与遍历性破缺的联系。除了自驱动系统之外，我们的结果表明活性玻璃中的老化尚未得到充分理解。
