Density Functional Theory Studies on Magnetic Manipulation in NiI2 Layers

Effective manipulation of magnetic states is fundamentally important to modern data storage and electronic devices that underpin the information age. Controlling magnetism via electric fields instead of magnetic fields has long been envisioned as a revolutionary technology to achieve higher energy efficiency and ultimate device miniaturization. The electric field paradigms, however, face major challenges of volatility, high energy cost, and low storage density. In this work, from density functional theory simulations, we developed effective approaches to achieve magnetic control in bilayer NiI2 via electrostatic doping and polarization field of the ferroelectric heterostructure. The interlayer antiferromagnetic (AFM) to ferromagnetic (FM) transition has been observed in bilayer NiI2 when the critical electron doping concentration reaches 0.625% due to the magnetic exchange competition between antiferromagnetic and ferromagnetic couplings. The critical concentration of magnetic transition can be reduced or increased depending on the polarization direction when it is placed on the ferroelectric substrate of Sc2CO2 as a result of polarization-induced interfacial electron transfer. Owing to the antiferromagnetic-to-ferromagnetic (AFM–FM) transition, the reversal of ferroelectric polarization modulates the electronic properties dramatically due to the strong interfacial magnetoelectric effect. The magnetic and electronic manipulation from electrostatic doping and polarization provides feasible approaches for next-generation electronics and spintronics.