Electronic and Magnetic Properties of Transition-Metal-Doped Monolayer Black Phosphorus by Defect Engineering

We investigate the structural, electronic, and magnetic properties of monolayer black phosphorus (M-BP) doped with 3d transition-metal elements by considering defects and defect complexes. The results show that pristine M-BP is nonmagnetic. P vacancy (V-P) can be magnetic with a rather high formation energy, and the (V-P + V-P) complex is nonmagnetic as well. Doping with transition metals of V, Cr, Mn, Fe, or Ni can induce magnetism, but Co doping will not. The magnetism is originated from their d orbitals. The formation energies of Mn, Co, and Fe doping can be significantly reduced with the existence of P vacancy by the formation of a substitutional and P vacancy (TMP + V-P) defect complex. In addition, (Co-P + V-P) has a magnetic moment of 0.10 mu(B), further demonstrating the important role of vacancy in the doping of transition-metal elements in M-BP.