DC spin generation by junctions with AC driven spin-orbit interaction

An unbiased one-dimensional weak link between two terminals, subjected to the Rashba spin-orbit interaction caused by an AC electric field which rotates periodically in the plane perpendicular to the link, is shown to inject spin-polarized electrons into the terminals. The injected spin polarization has a DC component along the link and a rotating transverse component in the perpendicular plane. In the low-rotation-frequency regime, these polarization components are proportional to the frequency. The DC component of the polarization vanishes for a linearly polarized electric field.

Figure 1

Schematic visualizations of devices proposed in the text. (a) A spin-orbit-active weak link connects two contacts, $L$ and $R$, to form a closed circuit [28]. The time-dependent spin-orbit interaction is generated by two perpendicular gates, whose potentials $V_y\left(t\right)$ and $V_z\left(t\right)$ oscillate slowly in time with frequency $\mathrm{\Omega }$. The arrows within the weak link indicate the directions in which polarized electron spins are flowing. (b) An open-circuit version of (a) where spin is accumulated in two terminals, leading to a magnetization that can be measured.