Melting of a macroscale binary Coulombic crystal.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Statistical Mechanics

Background:

• Melting of 2D crystals in thermal equilibrium is well-understood.
• Melting behavior of out-of-equilibrium 2D systems remains largely unresolved.
• Coulombic crystals offer a model for studying phase transitions due to tunable interactions.

Purpose of the Study:

• To investigate the melting dynamics of a 2D binary Coulombic crystal under shear.
• To determine the influence of impurities on the melting process.
• To clarify the mechanisms of shear-induced melting in systems with long-range interactions.

Main Methods:

• Fabrication of a 2D binary Coulombic crystal using tribocharged nylon and polytetrafluoroethylene (PTFE) beads.
• Induction of melting via agitation using an orbital shaker.
• Comparison of melting behavior in pure and impurity-doped (gold-coated nylon beads) crystals.

Main Results:

• Impurities were found to have no significant effect on the crystal's melting behavior.
• Shear-induced melting initiated from the crystal edges due to collisions with the container.
• Localized ordering persisted in some regions due to electrostatic interactions and favorable collisions.

Conclusions:

• The study clarifies the melting mechanisms of sheared 2D Coulombic crystals, highlighting the role of persistent long-range interactions.
• The findings suggest that specific conditions can render such materials resistant to disorder.
• This research provides insights into the stability and phase transitions of out-of-equilibrium condensed matter systems.