First-principles study of a Mn-doped In2Se3 monolayer: Coexistence of ferromagnetism and ferroelectricity with robust half-metallicity and enhanced polarization

Two-dimensional (2D) materials with coexistence of ferromagnetism (FM) and ferroelectricity (FE) are rare. By using first-principles modeling, here we report that doping of magnetic transition metal (TM) atoms in FE monolayer In2Se3 could introduce giant local FM magnetic moments (4 mu(B) per Mn atom). The exchange splitting energy, and the C-3 nu crystal field together with the hybridization of the Mn-d and Se-p orbitals result in spin-polarized states near the Fermi surface. More interestingly, the asymmetric charge distribution of the Jahn-Teller ion (Mn3+ d(4)) further lift the twofold degeneracy of the Mn-d el* states. This affects the band structure and enhances the FE polarization in monolayer In2Se3. Our work paves the way for tailoring FM in 2D FE via doping magnetic moments from TM atoms. The half-metallicity combined with the enhanced FE polarization make Mn-doped In2Se3 a candidate for potential applications in information technology and spintronic devices.