Self-alignment and anti-self-alignment suppress motility-induced phase separation in active systems

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Dense active matter systems exhibit complex collective behaviors.
• Motility-induced phase separation (MIPS) describes non-equilibrium coexistence in active matter.
• Self- and anti-self-alignment are key mechanisms influencing particle orientation and motion.

Purpose of the Study:

• To investigate the impact of self-alignment and anti-self-alignment on collective phenomena in dense active matter.
• To understand how these alignment mechanisms affect motility-induced phase separation (MIPS).

Main Methods:

• Theoretical analysis of effective torques influencing particle orientation.
• Study of MIPS in dense active granular systems.
• Application of scaling arguments to interpret results.

Main Results:

• Both self- and anti-self-alignment suppress clustering in MIPS.
• Increasing self-alignment leads to flocking within clusters and a homogeneous flocking phase.
• Anti-self-alignment induces a freezing phenomenon, suppressing MIPS and resulting in a homogeneous phase.

Conclusions:

• Self- and anti-self-alignment mechanisms play a crucial role in governing collective dynamics in dense active matter.
• These findings offer insights into phase separation and emergent behaviors.
• Results are experimentally verifiable in active granular systems.