Nonvolatile ferroelectric switching of room-temperature bipolar magnetic semiconductors for energy-efficient spintronics

Room-temperature magnetic semiconductors are crucial for next-generation spintronics, yet remain hindered by low Curie temperatures and volatile control mechanisms. Using density functional theory, we report Cr2NiSe4, a bipolar magnetic semiconductor (BMS) formed by Ni intercalation in bilayer CrSe2, with a Curie temperature of 495 K and a 0.40 eV band gap. We demonstrate nonvolatile control over carrier spin polarization in Al2Se3 heterostructures via ferroelectric switching: reversing the polarization of monolayer Al2Se3 induces a BMS-to-half-metal transition, whereas bilayer Al2Se3 enables half-metallic states with fully opposite spin polarization. This nonvolatile mechanism obviates the need for a continuous electric field and lowers energy consumption through interfacial charge transfer driven by ferroelectric band alignment. We propose a multiferroic memory device where ferroelectric polarization controls writing and spin-dependent conductance enables reading, enabling low-power, room-temperature operation. Our work establishes a feasible pathway for developing electrically tunable spintronics beyond the limits of Moore’s Law. Developing room-temperature magnetic semiconductors with robust, non-volatile electrical control remains a key challenge for energy-efficient spintronics. Here, first-principles calculations suggest that Ni-intercalated Cr2NiSe4, derived from bilayer CrSe2, is a 2D bipolar magnetic semiconductor with a Curie temperature of 495 K, in which ferroelectric switching in Al2Se3-based heterostructures enables non-volatile control of carrier spin polarization and room-temperature device operation.