  Moir\'e structures in small-angle-twisted bilayers of two-dimensional
semiconductors with a broken-symmetry interface form arrays of ferroelectric
domains with periodically alternating out-of-plane polarization. Here, we
propose a network theory for the tunability of such FE domain structure by
applying an electric field perpendicular to the 2D crystal. Using multiscale
analysis, we derive a fully parametrized string-theory-like description of the
domain wall network and show that it undergoes a qualitative change, after the
arcs of partial dislocation like domain walls merge (near the network nodes)
into streaks of perfect screw dislocations, which happens at a threshold
displacement field dependent on the DWN period.
