Quantum charge and spin pumping in monolayer phosphorene

Abstract

We study quantum-charge and spin-transport properties and the effects of in-plane strain on the charge and spin currents in a phosphorene monolayer using an adiabatic pumping regime. To achieve this goal, we proposed a device with three external ac gate voltages as oscillating potential barriers that are responsible for the generation of dc pumped current. Using exchange magnetic field induced by proximity effect of a ferromagnetic insulator, we determine the conditions in which fully spin-polarized current and pure spin current (with zero charge current) can be obtained. It is shown that the pumped current in the three-barrier case is about two times greater than the pumped current in a two-barrier system. The effect of strain is investigated and it is found that the spin current increases up to two orders of magnitude by applying the uniaxial strain which shows that the proposed device has high sensitivity to strain and could be used as straintronic devices such as strain switches and strain sensors. Also, in the same conditions, the pumped current in phosphorene is two, four, and five orders of magnitude greater than the pumped current in ${\mathrm{MoS}}_{2}$, silicene, and graphene, respectively. These properties show that phosphorene can be considered as a two- dimensional (2D) semiconductor with great potential for the fabrication of novel spintronic and straintronic devices that can overcome some of the limitations exhibited by conventional 2D materials.