Observation of fast sound in two-dimensional dusty plasma liquids

Abstract

Equilibrium molecular dynamics simulations are performed to study two-dimensional (2D) dusty plasma liquids. Based on the stochastic thermal motion of simulated particles, the longitudinal and transverse phonon spectra are calculated, and used to determine the corresponding dispersion relations. From there, the longitudinal and transverse sound speeds of 2D dusty plasma liquids are obtained. It is discovered that, for wavenumbers beyond the hydrodynamic regime, the longitudinal sound speed of a 2D dusty plasma liquid exceeds its adiabatic value, i.e., the so-called fast sound. This phenomenon appears at roughly the same length scale of the cutoff wavenumber for transverse waves, confirming its relation to the emergent solidity of liquids in the non-hydrodynamic regime. Using the thermodynamic and transport coefficients extracted from the previous studies, and relying on the Frenkel theory, the ratio of the longitudinal to the adiabatic sound speeds is derived analytically, providing the optimal conditions for fast sound, which are in quantitative agreement with the current simulation results.

v1: 7 pages, 6 figures

References in corpus (14)

• Crystallization dynamics of a single layer complex plasma
• Emergence and evolution of $k$-gap in spectra of liquid and supercritical states
• Magnetizing a complex plasma without a magnetic field
• Evolution of shear-induced melting in dusty plasma
• Universal law for the vibrational density of states of liquids
• Slow plastic creep of 2D dusty plasma solids
• Colloquium: Hydrodynamics and holography of charge density wave phases
• Deformations, relaxation and broken symmetries in liquids, solids and glasses: a unified topological field theory
• Explaining the specific heat of liquids based on instantaneous normal modes
• Onset of transverse (shear) waves in strongly-coupled Yukawa fluids
• Self-diffusion in two-dimensional quasi-magnetized rotating dusty plasmas
• Experimental Confirmation of the Universal Law for the Vibrational Density of States of Liquids
• Revealing the supercritical dynamics of dusty plasmas and their liquid-like to gas-like dynamical crossover
• Emergent Bistability and Switching in a Nonequilibrium Crystal

Cited by in corpus (3)

• Experimental observation of gapped shear waves and liquid-like to gas-like dynamical crossover in active granular matter
• Dynamical and thermodynamic crossovers in the supercritical region of a holographic superfluid model
• Revisiting the question of what instantaneous normal modes tell us about liquid dynamics