Ferroelectric modulated giant valley polarization and half metallicity in 2D RuBrF/Sc2CO2 multiferroic heterostructure for non-volatile memory applications

Controlling two-dimensional (2D) valleytronics is challenging for information technology. This study shows that a ferroelectric-assisted layer can effectively enable non-volatile control of 2D valleytronics. Using first-principles simulations, we find that different polarization states in the Sc2CO2 layer cause the RuBrF monolayer to transition from a semiconductor to a half-metal, while also changing magnetic anisotropy from in-plane to out-of-plane. In the −P state, the system behaves as a ferromagnetic semiconductor with a spontaneous valley polarization of 329 meV. In the +P state, it becomes a ferromagnetic half-metal, blocking valleytronics. This enables electro-reversible control of valley electrons in the RuBrF/Sc2CO2 heterostructure. We explain the modulation of magnetic anisotropy and valley polarization using second-order perturbation theory and the k⋅p model. Our work offers a promising approach for non-volatile valleytronic control at the nanoscale, aiding the design of new devices.