Cybermedia Center, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Nat Commun. 2017 Apr 11;8:14935. doi: 10.1038/ncomms14935.
For amorphous solids, it has been intensely debated whether the traditional view on solids, in terms of the ground state and harmonic low energy excitations on top of it, such as phonons, is still valid. Recent theoretical developments of amorphous solids revealed the possibility of unexpectedly complex free-energy landscapes where the simple harmonic picture breaks down. Here we demonstrate that standard rheological techniques can be used as powerful tools to examine nontrivial consequences of such complex free-energy landscapes. By extensive numerical simulations on a hard sphere glass under quasistatic shear at finite temperatures, we show that above the so-called Gardner transition density, the elasticity breaks down, the stress relaxation exhibits slow, and ageing dynamics and the apparent shear modulus becomes protocol-dependent. Being designed to be reproducible in laboratories, our approach may trigger explorations of the complex free-energy landscapes of a large variety of amorphous materials.
对于非晶固体，人们一直在激烈争论，传统的固体观点，即基于基态和其上的简谐低能量激发（如声子），是否仍然有效。最近对非晶固体的理论研究揭示了复杂的自由能景观的可能性，在这种景观中，简单的谐波图像会失效。在这里，我们证明标准的流变学技术可以用作强大的工具，来检验这种复杂的自由能景观的非平凡后果。通过在有限温度下对硬球玻璃进行准静态剪切的广泛数值模拟，我们表明，在所谓的加德纳转变密度以上，弹性会失效，应力松弛会表现出缓慢的、老化的动力学，并且表观剪切模量会变得依赖于协议。我们的方法旨在实验室中具有可重复性，可能会引发对各种非晶材料的复杂自由能景观的探索。
