Phases and fluctuations in a model for asymmetric inhomogeneous fluid membranes

TL;DR

This paper introduces a model for asymmetric fluid membranes that couples composition and curvature, revealing non-Ising critical behavior, phase transitions, and fluctuation enhancements unique to asymmetry, aligning with experimental observations.

Contribution

It presents a novel nonlinear coupling model for asymmetric membranes, predicting non-Ising phase behavior and fluctuation scaling, expanding understanding of membrane physics.

Findings

Asymmetric membranes exhibit non-Ising critical behavior.

Fluctuations scale with system size at critical points.

Symmetric membranes follow 2D Ising universality class.

Abstract

We propose and analyze a model for phase transitions in an inhomogeneous fluid membrane, that couples local composition with curvature nonlinearly. For asymmetric membranes, our model shows generic non-Ising behavior and the ensuing phase diagram displays either a first- or a second-order phase transition through a critical point (CP) or a tricritical point (TP), depending upon the bending modulus. It predicts generic nontrivial enhancement in fluctuations of asymmetric membranes that scales with system size in a power law fashion at the CP and TP in two dimensions, not observed in symmetric membranes. It also yields two-dimensional Ising universality class for symmetric membranes, in agreement with experimental results.