Dynamically phase-separated states in driven binary dusty plasma

TL;DR

This study uses simulations to explore how external forces cause phase separation into bands and lanes in a binary dusty plasma, revealing new scaling laws and conditions for structure formation.

Contribution

It introduces a detailed analysis of force-driven phase segregation in dusty plasmas, highlighting the role of interaction strength and revealing a 1/3 power law for domain growth.

Findings

Phase segregation occurs beyond a critical forcing threshold.

Lanes form predominantly under high external forcing.

Band and lane widths grow with a 1/3 exponent, contrasting equilibrium behavior.

Abstract

We comprehensively study external forcing-driven dynamical structure formation in a binary dusty plasma mixture. Using two-dimensional driven-dissipative molecular dynamics simulations, we demonstrate phase segregation into bands and lanes beyond a critical forcing threshold. The particles interact via the Debye-H\"uckel potential, with interaction strength serving as a control parameter for determining the critical forcing. During early evolution, the results exhibit features of two-stream instability. A steady-state phase-space diagram indicates that bands and lanes emerge beyond a critical forcing and coupling strength. Lanes predominantly form under high external forcing. Multiple independent diagnostics, including the order parameter, drift velocity, diffusion coefficients, domain size, and the final-to-initial coupling strength ratio, provide insight into phase segregation and help determine the critical forcing amplitude. Furthermore, we show that the time evolution of band and lane widths follows an exponent of 1/3 for both critical and off-critical mixtures. These findings contrast with the previously reported scaling of 1/2 for equilibrium phase separation in critical mixtures. These results help bridge the gap between dusty plasmas and colloidal systems and facilitate controlled dusty plasma experiments in this direction.