van der Waals Ferroelectric Engineering as a Universal Strategy for Nonvolatile Magnetic Switching in Nonmagnetic 2D VSiN₃

The presence of a van Hove singularity (vHS) at the Fermi level can trigger magnetic instability by mediating a spontaneous transition from paramagnetic to magnetically ordered states. While electrostatic doping (typically achieved via ionic gating) to shift the vHS to the Fermi level provides a general mechanism for engineering such magnetism, its volatile nature often leads to the collapse of induced states upon the gate field removal. Here, a novel scheme is presented for non-volatile magnetic control by utilizing ferroelectric heterostructures to achieve reversible magnetism switching. Using two-dimensional VSiN₃, a nonmagnetic material with Mexican-hat electronic band dispersions hosting vHSs, as a prototype, it is preliminarily demonstrated that both electron and hole doping can robustly induce magnetism. Further, by interfacing VSiN₃ with ferroelectric Sc₂CO₂, reversible switching of its magnetic state via polarization-driven heterointerfacial charge transfer is achieved. This mechanism enables a dynamic transition between insulating and half-metallic phases in VSiN₃, establishing a pathway to design multiferroic tunnel junctions with giant tunneling electroresistance or magnetoresistance. This work bridges non-volatile ferroelectric control with vHS-enhanced magnetism, opening opportunities for energy-effcient and high-performance spintronic devices and non-volatile memory devices.