Two-Dimensional Melting of a Crystal of Ferrofluid Spikes

TL;DR

This study observes a two-dimensional melting transition in a ferrofluid spike lattice, demonstrating a Lindemann criterion adherence and an intermediate hexatic phase, revealing parallels with solid-state 2D melting.

Contribution

It provides experimental evidence of 2D melting and hexatic phase formation in a ferrofluid spike system, linking out-of-equilibrium dynamics with classical melting theories.

Findings

Melting occurs at a critical spike displacement following the Lindemann criterion.

An intermediate hexatic-like phase is observed between solid and liquid phases.

The system exhibits behaviors analogous to 2D melting in solid-state physics.

Abstract

We report the observation of the transition from an ordered solid-like phase to a disordered liquid-like phase of a lattice of spikes on a ferrofluid surface submitted to horizontal sinusoidal vibrations. The melting transition occurs for a critical spike displacement which is experimentally found to follow the Lindemann criterion, for two different lattice topologies (hexagonal and square) and over a wide range of lattice wavelengths. An intermediate hexatic-like phase between the solid and isotropic liquid phases is also observed and characterized by standard correlation functions. This dissipative out-of-equilibrium system exhibits strong similarities with 2D melting in solid-state physics.