Atomically thin moiré materials behave like elastic membranes in which, at very small twist angles, the van der Waals stacking energy much exceeds the elastic energy. In this “marginal twist” regime, the equilibrium moiré consists of expanded regions with low stacking energy, which cover most of the moiré cell, while unfavorable stackings shrink to form topological defects linked by a periodic network of domain walls. We find analytical expressions that successfully capture this strong-coupling regime for both the triangular soliton network and the honeycomb soliton network, matching predictions from lammps molecular dynamics simulations, and numerical solutions of continuum elasticity theory. We find an emergent universality for which the theory is characterized by a single twist-angle dependent parameter. Our formalism is essential to understand experiments on a wide-range of materials of current interest, including twisted bilayer graphene, both aligned and antialigned stacked twisted ${\mathrm{WSe}}_2$ and twisted ${\mathrm{MoTe}}_2$, and any other twisted homobilayer with the same stacking symmetry.

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• Continuum mechanics
• Twistronics
• Transition metal dichalcogenides
• Twisted heterostructures
• van der Waals systems
• Molecular dynamics