C- and O-doped Hittorf's violet phosphorene as potential bipolar magnetic semiconductors from theoretical aspects

Hittorf’s violet phosphorene is a novel two-dimensional material with stable structure and excellent optoelectronic properties. Studying the doping effect helps to understand its physical essence and is of great significance for the further development of nanoelectronic devices. In this paper, the first-principles method based on density functional theory is used to study the electromagnetic properties of the non-metallic element B-, C-, N-, and O-doped single-layer violet phosphene. The results show that there is no magnetism after boron and nitrogen doping, and the system still behaves as a nonmagnetic semiconductor, while carbon and oxygen doping causes spin splitting, and the violet phosphorene transforms from a nonmagnetic semiconductor to a bipolar magnetic semiconductor, and its spin density is mainly distributed in the P atom and gap region, rather than on the impurity. The direction of spin polarization of its carrier can be reversed by adjusting the electric field of O-doped violet phosphorene. When a certain size of forward or reverse electrostatic field is applied, the band dispersion becomes stronger, and the O-doped violet phosphorene transforms into a half-metallic magnet with 100% downward or upward spin polarization at the Fermi level. The field effect spin filter based on O-doped violet phosphorene can reverse the direction of spin-polarized current by changing the direction of the gate voltage. This study shows that O-doped violet phosphorene is expected to be an ideal candidate material for two-dimensional spin field-effect transistors, bipolar magnetic spintronic devices, dual channel field effect spin filters, and field-effect spin valves.