Electrically-tunable spin polarization in boron-doped armchair black phosphorene nanoribbon

In two dimensional (2D) black phosphorene (BP), most of impurity atoms can introduce the highly local states near the Fermi level, but not necessarily bring spin polarization. The scientific community believes that one of the reasons may be that these impurity states are not partially filled by electrons. In this work, by first principle calculation, the coupling effects of the impurity atoms and the transverse electric field have been considered, our results indicate that the electric field can induce the spin polarization of the impurity states and convert the system from a semiconductor to a magnetic metal in the boron-doped armchair black phosphorene nanoribbons. Furthermore, the effect of electron doping has also been calculated, and we find that adding an extra electron to the system can also cause the spin splitting of the impurity subband and bring the transformation of the system from a semiconductor to a half metal and then to a magnetic semiconductor.