Achieving nonvolatile and multistate manipulation of charge-spin conversion, including the Edelstein effect (EE) and spin Hall effect (SHE), is crucial for high-density spintronic memory. Here, we propose a mechanism to simultaneously control both EE and SHE in two-dimensional ferroelectric bilayers, where interlayer-parallel and interlayer-antiparallel polarization configurations can coexist. Symmetry analysis shows that in the interlayer-parallel states, reversal of the total polarization switches the sign of the EE, whereas changing to an interlayer-antiparallel configuration suppresses the EE to zero, enabling electrically switchable current-induced spin accumulation among three distinct states that could be used for ternary logic operations. Meanwhile, the magnitude of the SHE can be tuned by switching between two different classes of polarization configurations (interlayer-parallel and interlayer-antiparallel). Using first-principles calculations, we demonstrate this mechanism in bilayer metallic ferroelectric ${\mathrm{PtBi}}_2$, where both interlayer-parallel and interlayer-antiparallel polarization configurations are energetically stable. The EE coefficient ${\chi }_{yx}$ in interlayer-parallel states, which reaches ${10}^9–{10}^{10}\hslash /\left(\text{A}\text{cm}\right)$ near the Fermi energy and can be reversed by polarization switching, arises from competing electron- and hole-pocket contributions near the Fermi surface. The intrinsic SHE coefficients, which are in the range of 100–1000 $(\hslash /e)\left(\text{S/cm}\right)$ near the Fermi energy, originate from spin Berry curvature that can be reshaped by polarization configuration variation and Fermi-level tuning. Our results establish ferroelectric bilayers as an all-in-one platform for electrically programmable charge-spin conversion.

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• Electronic structure
• Spin Hall effect
• Spin accumulation
• Spin-orbit coupling
• Spintronics
• 2-dimensional systems
• Density functional calculations