Giant valley splitting in a MoTe2/MnSe2 van der Waals heterostructure with room-temperature ferromagnetism

Abstract

An intrinsic large valley splitting has been realized in van der Waals (vdW) heterostructures formed by monolayer MoTe₂ and layered room-temperature ferromagnetic MnSe₂via first-principles calculations. The value of valley splitting of MoTe₂ can reach 106 meV among a variety of stacking MoTe₂/MnSe₂ heterobilayers, which is equivalent to the effective Zeeman splitting in an external magnetic field of 530 T. And the magnitude of valley splitting can be further enhanced by applying external vertical-stress and biaxial compressive strain. To obtain a higher operating temperature, a biaxial tensile strain of 2.3% has been applied on the monolayer MnSe₂ magnetic substrate, and the corresponding Curie temperature increased from an intrinsic value of 266 K to 353 K, but the valley splitting can still remain as large as 72 meV. This means that we can strike a balance between large valley splitting and high Curie temperature, which is vital for the application of magnetic valley electronic devices.