Mott transition and superexchange mechanism in magnetically doped XSi2N4 caused by large 3d orbital onsite Coulomb interaction

Magnetic two-dimensional materials have great potential in the preparation of nanoelectronic and spintronic devices. Recently, a new two-dimensional material with no corresponding bulk-structure, MoSi2N4, has been prepared, attracting public attention to the XA2Z4 series of materials. Naturally, doping with 3d magnetic element will result in various magnetic orderings. In our work, we replaced the Mo element with different transition-metal elements whose property varies from magnetic to nonmagnetic and screened out a variety of two-dimensional exchange scenarios. Then, we provided an analysis that shows the existence of a huge on-site Coulomb interaction at 3d orbitals which is strongly related to the Mott transition and therefore causes the superexchange interaction.

Automated summary

Magnetic two-dimensional materials show promise in nanoelectronic and spintronic device fabrication. The recent synthesis of the novel two-dimensional material MoSi2N4 has sparked interest in the XA2Z4 series of materials. Doping with 3d magnetic elements results in different magnetic arrangements. By replacing the Mo element with various transition metal elements, researchers identified multiple two-dimensional exchange scenarios and analyzed the significant on-site Coulomb interaction at 3d orbitals, which is closely related to the Mott transition and superexchange interaction.