Magneto-electronic property in zigzag phosphorene nanoribbons doped with transition metal atom

Abstract

The magneto-electronic properties of zigzag phosphorene nanoribbons (ZPNRs) doped, respectively, with iron (Fe), cobalt (Co) and nickel (Ni) atoms are investigated by the first-principles method based on density functional theory. The calculated results show that the structures of doped and undoped ZPNR are stable because their binding energy and Gibbs free energy are negative, and the Forcite annealing dynamics simulation shows that the thermal stabilities of all doped ZPNRs are extremely high. The ground states of pristine ZPNRs and ZPNRs doped with Co atoms are nonmagnetic states, while the ground states of ZPNRs doped with Fe or Ni atoms are ferromagnetic states. When they are in the nonmagnetic states, the pristine ZPNRs and ZPNRs doped with Co atoms turn into semiconductors, while the ZPNRs doped with Fe or Ni atoms become metals. The undoped ZPNRs are direct band gap semiconductors, while the ZPNRs doped with Co atoms are indirect band gap semiconductors, and the band gaps of the latter are smaller than those of the former. The changes of the properties of the ZPNRs are due to the introduction of impurity energy band into the energy band structures. The spin-polarized calculation displays that the pristine ZPNRs and ZPNRs doped with Co atoms are non-magnetic, and the ZPNRs doped with Fe or Ni atoms are magnetic but only in the ferromagnetic state. In the ferromagnetic state, the ZPNRs doped with Fe atoms are spin semiconductors, while the ZPNR doped with Ni atoms are spin half-metals. This means that the half-metal feature can be realized by doping Ni atom into ZPNR. The magnetism of ZPNRs doped with Fe or Ni atoms is mainly contributed by impurity atoms, and the occurrence of magnetism is due to the existence of unpaired electrons in ZPNR. The doping position has a certain influence on the electromagnetic properties of ZPNR. In the ferromagnetic state, the ZPNRs are half-metals when the Ni atoms are doped near the edge of the nanoribbons, while the ZPNRs are spin semiconductors as the Ni atoms are doped near the symmetric center of the nanoribbons. These results might be of significance for developing the phosphorene based electronic nanodevices