We present a Ginzburg-Landau theory of micro phase separation in a bidisperse
chiral membrane consisting of rods of opposite handendness. This model system
undergoes a phase transition from an equilibrium state where the two components
are completely phase separated to a microphase separated state composed of
domains of a finite size comparable to the twist penetration depth.
Characterizing the phenomenology using linear stability analysis and numerical
studies, we trace the origin of the discontinuous change in domain size that
occurs during this to a competition between the cost of creating an interface
and the gain in twist energy for small domains in which the twist penetrates
deep into the center of the domain