Lithium and Vanadium Intercalation into Bilayer V ₂ Se ₂ O: Ferrimagnetic–Ferroelastic Multiferroics and Anomalous and Spin Transport

Spin splitting in emerging altermagnets is nonrelativistic and momentum dependent, yet energy independent, and localized in momentum space, posing challenges for practical applications. Here, an intercalation-driven paradigm is proposed for altermagnets to attain ameliorative electronic structures, multiferroic characteristics, and anomalous and spin transport functionalities. As a representative system, electrochemistry- and self-intercalated V₂Se₂O bilayers are investigated, building on the recently reported room-temperature K- and Rb-intercalated V₂Se₂O family, utilizing density functional theory, Wannier function analyses, Monte Carlo simulations, and nonequilibrium Green's function methods. Intercalation induces room-temperature intralayer ferrimagnetic and interlayer ferromagnetic orders (358 K for Li intercalation and 773 K for V intercalation), ferroelasticity (≈1% signal intensity), in-plane uniaxial magnetic anisotropy, and metallization, while also modifying the anomalous Hall effect. Notably, Li- and V-intercalated V₂Se₂O bilayers exhibit enhanced spin splitting and half-metallic behavior, respectively, yielding near-perfect spin filtering efficiency. Intercalation substantially enhances spin transport in V₂Se₂O-based devices, enabling giant magnetoresistance (877%), ultrahigh thermal tunneling magnetoresistance (≈12 000%), and observable spin Seebeck and temperature negative differential resistance effects. This intercalation-driven paradigm expands altermagnetic functionalities through multifunctional integration, offering promising avenues for advanced, miniaturized, room-temperature exploitation of anomalous, electron, and spin transport properties.