Multiferroic Tuning of Magnetic Anisotropy in MnTe<sub>2</sub> Monolayer\nwith Li/Na Adsorption

Two-dimensional\n(2D) magnetic materials with tunable magnetic anisotropy\nenergy (MAE) are of great scientific interest and hold immense promise\nfor ultracompact spintronic devices with lower energy consumption\nand higher storage density. Here, we demonstrate a practical approach\nfor manipulating MAE in layered MnTe<sub>2</sub> through the alkali\nmetal adsorption and ferroelectric (FE) polarization effect. Our results\nreveal colossal MAE values of up to −12.428 erg/cm<sup>2</sup> under Li/Na adsorption, accompanied by a spin reorientation and\nenhanced ferromagnetic (FM) coupling stability. Their negative MAE\nshow a linear enhancement in response to the external strain. Moreover,\nwe find that the FE In<sub>2</sub>Se<sub>3</sub> substrate enhances\nthe perpendicular magnetic anisotropy (PMA) of MnTe<sub>2</sub> up\nto 2.318 erg/cm<sup>2</sup> depending on the polarization direction.\nFerroelectric switching at In<sub>2</sub>Se<sub>3</sub>-based interfaces\ncould also induce significant MAE changes with the value of 3.838\nerg/cm<sup>2</sup>. We elucidate that the underlying mechanisms for\nthese modulations are primarily attributed to alterations in the electron\noccupancy of interfacial Te<sub>1</sub>-derived <i>p</i><sub><i>y</i></sub> and <i>p</i><sub><i>z</i></sub> states, which affect their competitive spin–orbit\ncoupling (SOC) strengths. These findings highlight the potential of\ninterfacial engineering in tailoring magnetism in 2D materials, opening\nexciting possibilities for the development of advanced spintronic\ndevices with enhanced functionality.