Electrical control of valley polarization in two-dimensional systems has been intensively studied, yet existing approaches are largely limited to tuning its magnitude within a given band, without access to the distinct carrier and spin characteristics associated with different bands. Here, based on first-principles calculations, we demonstrate that ferroelectric polarization can be utilized to control magnetic proximity effects and realize band-selective valley polarization in two-dimensional heterostructures. Using monolayer $1T^{″}\text{−}{\mathrm{MoSe}}_2$ interfaced with ferromagnetic ${\mathrm{CrI}}_3$ as a model system, we show that polarization reversal redistributes the band-edge wave functions along the out-of-plane direction, thereby selectively modulating their coupling to the magnetic substrate. This leads to band-dependent proximity-induced exchange splitting, which is switched from the valence band to the conduction band. Since these bands correspond to different carrier types and opposite spin polarization, the polarization reversal enables switching not only the band hosting the valley-polarized carriers but also the associated valley Hall and spin Hall effects. Our results demonstrate an electrically controllable way to manipulate magnetic proximity effects and establish a mechanism for reconfigurable spin-valley transport in two-dimensional systems.

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• Valleytronics
• Ferroelectrics
• Multiferroics
• Transition metal dichalcogenides
• First-principles calculations