Regulation of transition temperature and magnetic anisotropy in 2D multiferroic monolayer through electron donating and withdrawing groups adsorption.

The discovery of two-dimensional (2D) magnetic materials ushers in the engineering of future magnetoelectric nanodevices and spintronics, however, it is limited by the lack of a material platform with simultaneously large magnetic anisotropy and high transition temperature. Using a recently synthesized CrSemonolayer as a demonstration, the impact on magnetism and electronics is studied via first-principles calculations by functionalizing the monolayer with electron-donating and electron-withdrawing groups namely NHand NO. The magnetic ground state of the CrSechanges from the stripe antiferromagnetic to the ferromagnetic state after functionalization. The transition temperature of CrSe-NOand CrSe-NHenhances to 105 and 70 K, respectively, due to the expansion of the CrSesuperlattice. Besides, the magnetic anisotropy energy (MAE) of the CrSe-NOincreases to 1.12 meV/Cr along the in-plane direction due to the electron-withdrawing effect of the NOgroup. Oppositely, the electron-donating effect will decrease the MAE. Moreover, robust out-of-plane electric polarization is induced into the functionalized CrSemonolayer, relying on the semiconducting nature and asymmetric geometry along thedirection. These findings demonstrate the critical role of functional groups in regulating the magnetic and electronic properties of 2D multiferroic structures, providing a general approach for controllable 2D spintronic applications.