Strong Zeeman splitting in orbital-hybridized valleytronic interfaces

Stacked heterointerfaces of two-dimensional (2D) materials are well-suited to obtain novel electronic functionality at small length scales, because the intrinsic properties of both materials can be blended by interlayer coupling with remarkable effects on the electronic band structure. In particular, band degeneracy at the K and K ' Brillouin zone valleys of 2D materials can be broken by symmetry reductions by applying an external magnetic field, with possible application in valleytronic devices. Nevertheless, this usually requires impractically large external magnetic fields > 100 T. An alternative and more practical route is provided via stacking a non-centrosymmetric layered material on a magnetic substrate to induce valley splitting through the magnetic proximity effect; however, the splitting magnitude can vary sharply between similar interfaces. In this work, first-principle calculations are used to calculate the valley splitting of eight low-strain interfaces with transition metal dichalcogenides stacked on 2D magnetic substrates. It is shown that the interlayer band hybridization plays a major role when the two layers' bands are closely aligned in energy, with the resulting band repulsion and the total valley splitting being strongly dependent on the Hubbard U correction, showing up to an order of magnitude change. The WSe2/CrGeTe3 interface in particular shows strong interlayer interactions, which can potentially lead to a significantly high valley splitting of 26 meV; however further experimental investigations will be needed to resolve uncertainties in the predicted valley splitting.

Automated summary

This study investigates the valley splitting of eight low-strain interfaces of transition metal dichalcogenides stacked on 2D magnetic substrates using first-principle calculations. The results show that interlayer band hybridization plays a major role in the valley splitting, which is strongly dependent on the Hubbard U correction. The WSe2/CrGeTe3 interface has particularly strong interlayer interactions and can potentially lead to a high valley splitting.