Phase transitions and membrane stiffness in a class of asymmetric heterogeneous fluid membranes

We propose a minimal model for miscibility phase transitions (MPTs) in a class of asymmetric two-component heterogeneous fluid membranes at equilibrium that generically display both first and second order MPTs, controlled by the interplay of asymmetry and heterogeneity. In the vicinity of the MPTs, the membrane fluctuations are generally enhanced. However, the degree of enhancement is found to depend sensitively on the asymmetry-heterogeneity coupling. We argue that experimental measurements of the membrane fluctuations at the MPTs should provide physical information about the forms of the asymmetry-heterogeneity couplings.