Long-wavelength fluctuations and anomalous dynamics in 2-dimensional liquids

• Main Authors: Li, Yan-Wei, Mishra, Chandan K., Sun, Zhao-Yan, Zhao, Kun, Mason, Thomas G., Ganapathy, Rajesh, Pica Ciamarra, Massimo
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2020
• Subjects: Science::Physics; Long-wavelength Fluctuations; Diffusion
• Online Access: https://hdl.handle.net/10356/144515
• Institution: Nanyang Technological University

In 2-dimensional systems at finite temperature, long-wavelength Mermin-Wagner fluctuations prevent the existence of translational long-range order. Their dynamical signature, which is the divergence of the vibrational amplitude with the system size, also affects disordered solids, and it washes out the transient solid-like response generally exhibited by liquids cooled below their melting temperatures. Through a combined numerical and experimental investigation, here we show that long-wavelength fluctuations are also relevant at high temperature, where the liquid dynamics do not reveal a transient solid-like response. In this regime, these fluctuations induce an unusual but ubiquitous decoupling between long-time diffusion coefficient D and structural relaxation time τ, where [Formula: see text], with [Formula: see text] Long-wavelength fluctuations have a negligible influence on the relaxation dynamics only at extremely high temperatures in molecular liquids or at extremely low densities in colloidal systems.