Inadequacy of the extrapolation-length method for modeling the interface of a ferroelectric-graphene heterostructure

To study a ferroelectric-graphene heterostructure, we employ Ginzburg-Landau-Devonshire theory in conjunction with Kretschmer and Binder's extrapolation-length method for modeling interface lattice relaxation. We rigorously justify a selection of model parameters that we use to predict the properties of a system consisting of the ferroelectric lithium niobate (LiNbO₃) (0001) sandwiched between graphene monolayers. By comparing our results to those from first-principles density-functional theory calculations performed by Baeumer et al. [Nat. Commun. 6, 6136 (2015)] for the equivalent system, we demonstrate the inadequacy of the extrapolation-length method for modeling this system. We discuss the relevance of our work to predicting electrical gating.