Sprakel Joris, Zaccone Alessio, Spaepen Frans, Schall Peter, Weitz David A
School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2017 Feb 24;118(8):088003. doi: 10.1103/PhysRevLett.118.088003. Epub 2017 Feb 23.
Crystals with low latent heat are predicted to melt from an entropically stabilized body-centered cubic symmetry. At this weakly first-order transition, strongly correlated fluctuations are expected to emerge, which could change the nature of the transition. Here we show how large fluctuations stabilize bcc crystals formed from charged colloids, giving rise to strongly power-law correlated heterogeneous dynamics. Moreover, we find that significant nonaffine particle displacements lead to a vanishing of the nonaffine shear modulus at the transition. We interpret these observations by reformulating the Born-Huang theory to account for nonaffinity, illustrating a scenario of ordered solids reaching a state where classical lattice dynamics fail.
具有低潜热的晶体预计会从熵稳定的体心立方对称结构中熔化。在这个弱一级相变中，预计会出现强关联涨落，这可能会改变相变的性质。在这里，我们展示了大的涨落如何稳定由带电胶体形成的体心立方晶体，从而产生强幂律关联的非均匀动力学。此外，我们发现显著的非仿射粒子位移导致在相变处非仿射剪切模量消失。我们通过重新表述玻恩 - 黄理论以考虑非仿射性来解释这些观察结果，说明了有序固体达到经典晶格动力学失效状态的一种情形。
