Designing the weak Fermi pinning and ferromagnetic van der Waals contacts to bilayer CrI3

Abstract

In this work, we conduct comprehensive first-principles computations on van der Waals (vdW) contacts between two-dimensional (2D) metals and bilayer CrI3. This study examines the Fermi level pinning (FLP) effect, interface tunneling, magnetic phase transition temperatures, and magnetic anisotropy energy (MAE) in these heterostructures. Research outputs indicate that, except for the graphene (Gra)/CrI3 heterostructure, the vdW contacts may effectively suppress the strong FLP effect in the interface regions of 2D metal/CrI3 systems. Further analyses reveal that the strong FLP effect in the Gra/CrI3 system originates from large intrinsic interface dipoles. Additionally, the magnetic ground state calculations suggest that the intrinsic antiferromagnetism of bilayer CrI3 can be modulated into ferromagnetism when contacted with 2D metals. By using the classical Monte Carlo simulations combined with the magnetic exchange Heisenberg model, we predict the Curie temperatures of various 2D metal/bilayer CrI3 systems. The Curie temperature of CrI3/NbSe2 is 63 K, which is approximately twice that of CrI3/TaSe2(34 K). Additionally, for all heterostructures, we characterized the interface transport for all heterostructures based on the Simmons model and calculated the MAE. These findings may provide a paradigm for designing those multifunctional 2D spintronic devices in electrical engineering.