Chiral Altermagnetic Magnetoelectrics

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) ${}_3$ ] as a promising material platform. K[Co(HCOO) ${}_3$ ] 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.