Electroferrofluids with nonequilibrium voltage-controlled magnetism, diffuse interfaces, and patterns

Area of Science:

• Colloid Science
• Non-equilibrium Physics
• Materials Science

Background:

• Driving matter to nonequilibrium states can yield emergent behaviors and functionalities.
• Uniform colloidal dispersions typically exist in equilibrium states.

Purpose of the Study:

• To demonstrate that uniform colloidal dispersions can be driven into dissipative nonuniform states with emergent behaviors.
• To explore voltage-controlled magnetism and novel dissipative patterns in such systems.

Main Methods:

• Experimentally driving weakly charged superparamagnetic iron oxide nanoparticles in a nonpolar solvent using electric fields.
• Analyzing the formation of nonequilibrium concentration gradients and their impact on magnetic properties.
• Quantifying dissipation and linking it to observed pattern formation.

Main Results:

• Achieved dissipative nonuniform states from uniform colloidal dispersions.
• Observed voltage-controlled magnetization and susceptibility.
• Discovered novel dissipative patterns arising from concentration gradients acting as diffuse interfaces.

Conclusions:

• Uniform colloidal dispersions can be controllably driven into functional nonequilibrium states.
• This approach enables emergent properties like voltage-controlled magnetism and responsive patterns.
• The concept is generalizable to various functional colloids for diverse responses beyond equilibrium limitations.