The unexpected magnetism in 2D group-IV-doped GaN for spintronic applications

In this study, we systematically investigated the structural and magnetic properties of group-IV-doped monolayer GaN by first-principles calculations. Among the group-IV element, only Ge and Sn atoms with large atomic radii can form a buckling substituted doping structure with an in-plane magnetic moment of 1 mu(B) per dopant. The compressive strains enhance the in-plane magnetic anisotropy, while tensile strains tend to destroy the magnetic moment of dopants. Both Ge and Sn atoms can stay on the same side of monolayer GaN to form anti-ferromagnetic semiconductors due to the large diffusion barrier for crossing to the monolayer GaN. The intrinsic Ga or N vacancies will eliminate the magnetic moments of group-IV dopants due to the charge transferring from the dopants to intrinsic vacancies. The N-rich growth conditions and a plentiful supply of Ge or Sn dopants to fill the intrinsic vacancies help to maintain the magnetic properties of group-IV-doped monolayer GaN.