双轴应变调控二维单层C2X2TM (X=O, H; TM=Fe, Cr)的多铁性研究.

Using first principles calculations based on the density functional theory, we systematically studied the magnetic and ferroelectric properties of two-dimensional monolayer C2 X2TM (X=O, H; TM=Fe, Cr), where monolayer oxidized/hydrogenated graphene is intercalated by transition metal atoms Fe and Cr. Considering the electron in-situ Coulomb interaction and spin orbit coupling, the stable structure and ground state magnetic structure of two-dimensional monolayer C2 X2TM are obtained. The changes of magnetism, energy band, ferroelectric polarization and electronic structure of C2 X2TM under different strains are studied in detail. The results show that the barrier height and energy gap of the system can be effectively controlled by adding biaxial strain, but the chiral counterclockwise antiferromagnetic structure is remained. It is found that C2O2Cr at 25% strain and C2 O2Fe at 30% strain monolayer films have ferroelectric polarization and reversal barriers similar to those of two-dimensional ferroelectric materials such as GeS. These results indicate that C2 O2Fe (Cr) monolayer film is a new two-dimensional multiferroic material with coexisting ferroelectricity (FE) and antiferromagnet (AFM) order. [ABSTRACT FROM AUTHOR]