Chiral Altermagnetic Magnetoelectrics

ABSTRACT In this work, we introduce a new class of chiral altermagnetic magnetoelectrics in structurally chiral, nonpolar altermagnetic systems and identify the experimentally well‐characterized three‐dimensional metal–organic framework K[Co(HCOO)] as a promising material platform. K[Co(HCOO)] exhibits chirality‐locked g ‐wave altermagnetic spin splitting together with dual‐mode switchable electric polarization controlled by Néel‐vector reorientation and structural chirality. Specifically, Néel‐vector reorientation generates a finite electric polarization and reverses its sign, whereas chirality switching between left‐ and right‐handed enantiomers produces an additional sign reversal. The associated electronic and optical responses provide effective readout channels for these switchable states. Our results establish chiral altermagnetic magnetoelectrics as a promising route to chirality‐ and Néel‐vector‐controlled nonvolatile multifunctional spintronics.