Non-adiabatic generation of a pure spin current in a 1D quantum ring with spin-orbit interaction

TL;DR

This paper theoretically shows that a pure spin current can be generated in a 1D quantum ring with spin-orbit interaction using a non-adiabatic, two-component terahertz laser pulse with spatial asymmetry, revealing conditions for optimal spin current without charge flow.

Contribution

It introduces a method to generate pure spin currents in a quantum ring via non-adiabatic laser pulses, analyzing the effects of spatial asymmetry and spin-orbit coupling.

Findings

Critical dephasing angles suppress charge current

Maximum and minimum spin currents occur at specific angles

Stationary solutions for density operator are derived

Abstract

We demonstrate the theoretical possibility of obtaining a pure spin current in a 1D ring with spin-orbit interaction by irradiation with a non-adiabatic, two-component terahertz laser pulse, whose spatial asymmetry is reflected by an internal dephasing angle $\phi$. The stationary solutions of the equation of motion for the density operator are obtained for a spin-orbit coupling linear in the electron momentum (Rashba) and used to calculate the time-dependent charge and spin currents. We find that there are critical values of $\phi$ at which the charge current disappears, while the spin current reaches a maximum or a minimum value.