Valley polarization and biaxial strain dependent conductivity of WS2/SrRuO3(111) heterostructures

The electronic structures of monolayer WS2 on top of bilayer SrRuO3(1 1 1) are studied by first-principles calculations with spin-orbital coupling. The electronic properties can be influenced by stacking patterns of WS2/SrRuO3(1 1 1) heterostructures. Meanwhile, the valley polarization can be induced in monolayer WS2 due to the broken time-reversal symmetry by the proximity to bilayer SrRuO3(1 1 1). With particular stacking patterns, larger valley splitting of monolayer WS2 obtained in A1, A3, A4 and A5 models is 11.2, 11.3, 11.1 and 11.1 meV, respectively. Moreover, with biaxial strains, the conductivity of monolayer WS2 can be effectively modulated. The Fermi level moves to a higher energy by appling tensile strains. Then the conductivity of WS2 is governed by the valley states. In addition, the mechanical strains can modify the valley polarization and band gap effectively, showing potential applications in spintronic and valleytronic devices.