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arXiv · 1905.13593

Long-wavelength fluctuations and anomalous dynamics in two-dimensional liquids

Yanwei Li·Chandan K. Mishra·Zhaoyan Sun·Kun Zhao·Thomas G. Mason·Rajesh Ganapathy·Massimo Pica Ciamarra
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Abstract

Long-wavelength Mermin-Wagner fluctuations prevent the existence of translational long-range order, in two-dimensional systems at finite temperature. Their dynamical signature, which is the divergence of the vibrational amplitude with the system size, also affects disordered solids and washes out the transient solid-like response generally exhibited by liquids cooled below their melting temperature. Through a combined numerical and experimental investigation, here we show that long-wavelength fluctuations are also relevant at high temperature, where the liquid dynamics does not reveal a transient solid-like response. In this regime, they induce an unusual but ubiquitous decoupling between long-time diffusion coefficient $D$ and structural relaxation time $\tau$, where $D\propto \tau^{-\kappa}$, with $\kappa > 1$. Long-wavelength fluctuations have a negligible influence on the relaxation dynamics only at extremely high temperatures, in molecular liquids, or extremely low densities, in colloidal systems.

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Yanwei Li, Chandan K. Mishra, Zhaoyan Sun, Kun Zhao, Thomas G. Mason, Rajesh Ganapathy, Massimo Pica Ciamarra. 2019-05-31. Long-wavelength fluctuations and anomalous dynamics in two-dimensional liquids. https://doi.org/10.1073/pnas.1909319116

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