A spin pump turnstile: parametric pumping of a spin-polarized current through a nearly-closed quantum dot

TL;DR

This paper explores a quantum dot turnstile device that uses parametric pumping to generate a controllable, spin-polarized current, functioning as a spin filter and spin injector with potential applications in spintronics.

Contribution

It introduces a novel quantum dot turnstile mechanism for parametric pumping of spin-polarized currents, analyzing its quantum dynamics and operational limits.

Findings

Device can operate as a pure spin pump.

Capable of acting as a controllable spin filter.

Potential for on-demand spin injection.

Abstract

We investigate parametric pumping of a spin-polarized current through a nearly-closed quantum dot in a perpendicular magnetic field. Pumping is achieved by tuning the tunnel couplings to the left and right lead - thereby operating the quantum dot as a turnstile - and changing either the magnetic field or a gate-voltage. We analyze the quantum dynamics of a pumping cycle and the limiting time scales for operating the quantum dot turnstile as a pure spin pump. The proposed device can be used as a fully controllable double-sided and bipolar spin filter and to inject spins "on demand".