Spin-polarized currents in double and triple quantum dots driven by ac magnetic fields

TL;DR

This paper investigates how ac and dc magnetic fields can be used to generate highly spin-polarized currents in double and triple quantum dots, with potential applications in spintronic devices.

Contribution

It demonstrates that tuning Zeeman level energies via gate voltages enables controllable spin filtering and inversion in quantum dot systems under magnetic fields.

Findings

Double quantum dots can act as spin-up or spin-down filters.

Triple quantum dots can serve as spin filters and inverters.

Strongly spin-polarized currents are achievable through energy level tuning.

Abstract

We analyze transport through both a double quantum dot and a triple quantum dot with inhomogeneous Zeeman splittings in the presence of crossed dc and ac magnetic fields. We find that strongly spin-polarized current can be achieved by tuning the relative energies of the Zeeman-split levels of the dots, by means of electric gate voltages: depending on the energy level detuning, the double quantum dot works either as spin-up or spin-down filter. We show that a triple quantum dot in series under crossed dc and ac magnetic fields can act not only as spin-filter but also as spin-inverter.