Criticality in a non-equilibrium, driven system: charged colloidal rods (fd-viruses) in electric fields

Area of Science:

• Soft matter physics
• Non-equilibrium statistical mechanics
• Colloidal science

Background:

• Charged colloidal rods (fd-virus particles) are model systems for studying phase transitions.
• External electric fields can induce novel phases and states in colloidal suspensions.
• Understanding non-equilibrium critical phenomena is crucial for complex systems.

Purpose of the Study:

• To identify and characterize a non-equilibrium critical point in charged colloidal rod suspensions.
• To investigate the behavior of field-induced phases and states.
• To compare critical phenomena in driven systems with classical equilibrium systems.

Main Methods:

• Experiments on suspensions of charged colloidal rods (fd-virus particles).
• Application of external electric fields to induce phase transitions.
• Characterization of off-critical and critical behavior, including power law and logarithmic divergencies.

Main Results:

• A non-equilibrium critical point was identified in the electric field-driven colloidal system.
• Multiple transition lines of field-induced phases converge at this critical point.
• Diverging length and time scales were observed at the non-equilibrium critical point, analogous to equilibrium systems.

Conclusions:

• Driven systems far from equilibrium can exhibit critical phenomena similar to equilibrium systems.
• Non-equilibrium critical points can serve as meeting points for various field-induced phases.
• These findings extend the universality of critical phenomena to non-equilibrium conditions.