Activity-driven demixing and sustained temperature gradients in inertial active-passive mixtures

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Traditional thermodynamics assumes uniform temperature in coexisting phases.
• Active matter systems exhibit nonequilibrium phenomena like motility-induced phase separation.
• Understanding hybrid active-passive systems is crucial for novel material design.

Purpose of the Study:

• Investigate particle demixing and temperature gradients in binary mixtures of inertial active and passive particles.
• Explore the role of particle inertia and self-propulsion strength in nonequilibrium phenomena.
• Elucidate the fundamental principles of self-organization in active matter.

Main Methods:

• Simulations of binary mixtures of inertial active and passive particles.
• Analysis of particle demixing dynamics.
• Measurement of emergent temperature gradients and kinetic temperatures.

Main Results:

• Pronounced particle demixing and significant hot-cold coexistence observed within specific parameter ranges.
• Activity differences drive rapid species separation, enhanced by rotational diffusion.
• Synergy between inertia and activity amplifies temperature differences between species and phases.

Conclusions:

• Active-passive mixtures can sustain kinetic temperature gradients, circumventing thermal homogenization.
• Inertia-enabled energy storage and propulsion contribute to temperature disparities.
• Findings offer insights into nonequilibrium self-organization with applications in bio-inspired materials and energy transport.