Role of oxygen in enhancing magnetism of Fe-doped MoSi2N4 monolayer from first-principles study

MoSi2N4 is a new type of two-dimensional layered material, which is semiconducting with novel valley-physics properties and excellent stability, suggesting its great applications in the field of valleytronics and spintronics. In present work, the spin-polarized electronic structure and magnetic properties of different doping models of MoSi2N4 are investigated based on first principles. The results show that Fe doping presents a semi-metallic band structure, inducing a total magnetic moment of 4.01 mu B. For Fe + O co-doping configuration, further introduction of the O atom increases the total magnetic moment to 5.0 mu B. The magnetic moments mainly originate from the coupling of Fe-3d and O-2p and Mo-4d and O-2p. Then, the calculations show that the stability of Fe + O + Fe codoping configuration is enhanced and exhibits antiferromagnetic order with a total magnetic moment of about 0.98 mu B. Due to the antiferromagnetic interaction, the magnetic moment is mainly derived from the hybridization of Mo-4d and O-2p states, and a transition from semi-metallic to metallic band structure is observed.