Magnetic properties of SnSe monolayer doped by transition-metal atoms: A first-principle calculation

Using the first-principles calculations, we investigate the structural, electronic, and magnetic properties of 3d transition metal (TM) (TM = Co, Cu, Mn, Fe, and Ni) atoms substitutional doping of SnSe monolayer. Magnetism is observed for Co, Mn, Fe, and Ni doping. In particular, Mn- and Fe-substituted systems exhibit large magnetic moment of 5.0 and 4.0 mu B at a very low impurity concentration. Then, we study the magnetic coupling in these two substituted systems. The magnetic coupling between two Mn atoms prefers to antiferromagnetic (AFM) owing to the super exchange between d states of two Mn atoms. Interestingly, both AFM and ferromagnetic (FM) coupling are observed in two-Fe-doped systems. Due to the strong spin-orbit coupling between Fe-3d and Se-4p, a long-range FM interaction is found in the Fe-substituted system. Our results demonstrate potential applications of TM-substituted SnSe for spintronics and magnetic storage devices.