The sliding phase transition in ferroelectric van der Waals bilayers

We address the sliding thermodynamics of van der Waals-bonded bilayers by the continuum elasticity theory. We attribute the robustness of the ferroelectricity recently observed in h-BN and WTe2 bilayers to large monolayer in-plane stiffness. We compute the electric susceptibility and specific heat in the mean-field self-consistent phonon approximation. We compare critical temperatures and electric switching fields with the observations.