Band‐Rearrangement‐Enabled Nonvolatile Altermagnetism Switching in 2D Ferroelectric/Magnetic Heterostructures

Abstract Altermagnetism, a newly discovered class of collinear magnets, combines spin polarization with antiparallel magnetization, offering groundbreaking opportunities for designing multiferroic materials. Here, a novel mechanism is theoretically proposed for achieving significant nonvolatile modulation of altermagnetic spin‐splitting in the MnPTe 3 /In 2 Se 3 heterostructure through magnetoelectric coupling through interfacial band rearrangement. First‐principles calculations demonstrate that the ferroelectric polarization of In 2 Se 3 not only drives the transition of MnPTe 3 from antiferromagnetism to altermagnetism but also enables reversible electrical control of spin‐splitting from 5.31 to 20.11 meV via polarization switching. Crucially, this effect stems from interfacial charge transfer‐induced band realignment, where the built‐in electric field shifts the dominant valence band maximum contribution between the magnetic and ferroelectric layers, thereby controlling spin‐splitting near the Fermi level. The effect is further verified by a pronounced magneto‐optical Kerr response, with Kerr rotation angles reaching −0.18° in the ‐ P state. This work establishes a band‐engineering approach for nonvolatile altermagnetic control, providing a theoretical foundation for high‐efficiency spintronic devices.