High Performance Room Temperature Multiferroic Properties of <i>w</i> ‐MnSe Altermagnet

Abstract Altermagnetism and ferroelectricity are reported in certain materials. However, the possibility of their coexistence or interplay in a single‐material phase remains an open question. Here, the multiferroicity in hexagonal wurtzite MnSe ( w ‐MnSe) is explored via first‐principles calculations. The w ‐MnSe exhibits an altermagnet semiconducting nature characterized by a direct bandgap of 1.98 eV and spin splitting of up to 245 meV in the valence band structure. The w ‐MnSe has an in‐plane magnetic anisotropy energy (MAE) of −31 µeV per cell along the a ‐direction and a Néel temperature ( T N ) of ≈405 K. Besides, the w ‐MnSe exhibits a giant out‐of‐plane spontaneous electric polarization of 53 µC cm − 2 and a moderate energy barrier of 0.37 eV f.u −1 . The ferroelectric critical temperature ( T C ) of 965 K is obtained, and this may indicate excellent thermal stability. The correlation is postulated between altermagnetim and ferroelectricity to control spin orientation mediated by the rotation of polyhedra formed by nonmagnetic elements within the lattice structure. The finding implies that the w ‐MnSe can be a potential material for future‐generation multiferroic devices that operate above room temperature.