Tunable valley splitting in two-dimensional CrBr 3 /VSe 2 van der Waals heterostructure under strains and electric fields.

Valleytronics opens up fascinating opportunities for using the valley degree of freedom in information storage and quantum computation. Here, based on the first-principles calculations, we investigate the effects of biaxial strains and electric fields on the magnetic, electronic, and valleytronic properties of two-dimensional CrBr 3 /VSe 2 van der Waals heterostructure consisting of two ferromagnetic monolayers. An interlayer magnetic phase transition from parallel to antiparallel is found when a compressive strain exceeds -2% or a tensile strain exceeds 4% is applied, while the interlayer magnetic configuration remains parallel under perpendicular electric fields. The valley splitting in the conduction bands is significantly enhanced by a compressive strain or an electric field pointing from the VSe 2 to the CrBr 3 layer. Specifically, a large valley splitting about 30.8 meV is obtained in the system with antiparallel interlayer magnetic under a compressive strain of -4%, which is more than three times that of pristine CrBr 3 /VSe 2 heterostructure. Our findings provide new insights into the future valleytronic applications for two-dimensional magnetic van der Waals heterostructures.