Modulation of Electronic and Magnetic Properties for 2H–FeCl₂ Monolayer Using the Ferroelectric LiNbO₃(0001) Substrate

Using first-principles calculations, we systematically investigate the interfacial coupling and charge transfer mechanisms of the 2H–FeCl 2 /LiNbO 3 (0001) heterostructure, exploring the effect of the LiNbO 3 (0001) substrate on the magnetic and electronic properties of the 2H–FeCl 2 overlayer. Our result reveals a ionic-van der Waals coupling between the 2H–FeCl 2 monolayer and LiNbO 3 (0001) substrate, with predominately ionic bonding character. The interface charge transfer effect in the 2H–FeCl 2 /LiNbO 3 (0001) heterostructure is codetermined by both band alignment and interface local chemical environments and shows remarkable sensitivity to the ferroelectric polarization direction of the LiNbO 3 (0001) substrate, suggesting this system as a promising platform for developing ferroelectric field-effect transistors. Remarkably, the electronic and magnetic properties of the 2H–FeCl 2 overlayer are significantly modified by the LiNbO 3 (0001) substrate. Although the pristine 2H–FeCl 2 monolayer exhibits ferromagnetic order, the 2H–FeCl 2 overlayer on both the negative and positive LiNbO 3 (0001) polarized substrate transforms into ferrimagnetism. Furthermore, the polarization reversal of the positive polarized LiNbO 3 (0001) substrate induces half-metal characteristics and p-type doping in the 2H–FeCl 2 overlayer. These findings establish the 2H–FeCl 2 /LiNbO 3 (0001) heterostructure as a composite multiferroic material with an exceptional potential for spintronic and optoelectronic devices.