Mobility-induced order in active XY spins on a substrate

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Active matter systems exhibit complex emergent behaviors.
• Understanding phase ordering and stability in driven systems is crucial.
• Existing models often lack a unified framework for diverse active phenomena.

Purpose of the Study:

• To investigate the stability of phase-ordered active XY spins in contact with a diffusing species.
• To characterize the orientational order and density fluctuations in these systems.
• To establish a theoretical framework applicable to various active matter systems.

Main Methods:

• Development of a theoretical model for active spinners on a substrate.
• Analysis of generalized quasi-long-range order (QLRO).
• Investigation of number fluctuations, including hyperuniformity and giant fluctuations.

Main Results:

• Stable, uniform phases of active XY spins are identified, robust against noise.
• Two distinct types of generalized QLRO are observed, stronger or weaker than equilibrium QLRO.
• Nonuniversal scaling of phase and density fluctuations dependent on nonlinear couplings.

Conclusions:

• A direct correspondence exists between orientational order and number fluctuations.
• The model provides a minimal yet versatile framework for active superfluids, cilia, and membranes.
• Nonlinear dynamics dictate the emergent properties of these active systems.