论文标题

无定形固体中的紧急弹性

Emergent Elasticity in Amorphous Solids

论文作者

Nampoothiri, Jishnu N., Wang, Yinqiao, Ramola, Kabir, Zhang, Jie, Bhattacharjee, Subhro, Chakraborty, Bulbul

论文摘要

自然丰富的无定形固体(例如凝胶,危害颗粒和生物组织)的机械响应未通过定义晶体弹性的破碎对称性的常规范式来描述。相比之下,这种静脉固体的响应受机械平衡的局部条件,即其成分的力和扭矩平衡。在这里,我们表明这些约束具有广义电磁学的数学结构,其中静电极限成功捕获了无定形固体的各向异性弹性。局部机械约束弹性的出现为没有断裂的对称性的系统提供了一种新的范式,类似于量子旋转液体的新兴量表理论。具体而言,我们的$ u(1)$ rank-2对称张量规弹性理论转化为物质分数相的电磁学,其应力映射到电位移和矢量电荷的力。我们通过在两个和三个维度中对无摩擦磁盘的数值模拟来证实我们的理论结果,并在两个维度上对摩擦磁盘进行了实验。我们还提供了实验证据,表明颗粒培养基中的力链是类似于分形码的无定形弹性的亚维激发。

The mechanical response of naturally abundant amorphous solids such as gels, jammed grains, and biological tissues are not described by the conventional paradigm of broken symmetry that defines crystalline elasticity. In contrast, the response of such athermal solids are governed by local conditions of mechanical equilibrium, i.e., force and torque balance of its constituents. Here we show that these constraints have the mathematical structure of a generalized electromagnetism, where the electrostatic limit successfully captures the anisotropic elasticity of amorphous solids. The emergence of elasticity from local mechanical constraints offers a new paradigm for systems with no broken symmetry, analogous to emergent gauge theories of quantum spin liquids. Specifically, our $U(1)$ rank-2 symmetric tensor gauge theory of elasticity translates to the electromagnetism of fractonic phases of matter with the stress mapped to electric displacement and forces to vector charges. We corroborate our theoretical results with numerical simulations of soft frictionless disks in both two and three dimensions, and experiments on frictional disks in two dimensions. We also present experimental evidence indicating that force chains in granular media are sub-dimensional excitations of amorphous elasticity similar to fractons.

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