Enhanced Intralayer Ferromagnetism in CrI3 by Interfacial Super-Superexchange Interaction

Manipulating the interlayer exchange interaction in two-dimensional (2D) layered materials is crucial for achieving intrinsic long-range magnetic ordering for high-performance spintronic devices. In this work, we propose a general and experimentally feasible approach to enhance the ferromagnetism of a monolayer material in van der Waals (vdW) heterostructures by taking advantage of the interfacial super-superexchange interaction. As a proof of concept, we consider the CrI3/Fe3GeTe2 heterostructure with a strong Cr–I···Te–Fe super-superexchange interaction. Our first-principles calculations show that the interlayer distance and electronic coupling between CrI3 and Fe3GeTe2 sheets highly depend on their stacking geometry, exhibiting distinct weak and strong coupling regions. Specifically, a Cr–I–Te angle of ∼103° leads to the strongest interfacial coupling, robust ferromagnetism for the interlayer spin configuration, and enhanced Curie temperature of the CrI3 monolayer by nearly two fold.