Coulomb interactions induced perfect spin filtering effect in a quadruple quantum-dot cell

TL;DR

This paper proposes a quadruple quantum-dot cell as a spin filter, demonstrating that Coulomb interactions induce spin-polarized windows in conductance, which can be controlled by gate fields and dot coupling.

Contribution

The study introduces a novel quadruple quantum-dot design and a Green's function approach to analyze Coulomb interaction effects on spin filtering, highlighting controllable spin-polarized windows.

Findings

Coulomb correlations create insulating bands leading to spin-polarized windows.

Spin polarization can be tuned by gate voltages.

Hopping between dots affects the spin filtering efficiency.

Abstract

A quadruple quantum-dot (QQD) cell is proposed as a spin filter. The transport properties of the QQD cell were studied in linear response regime on the basis of the equations of motion for retarded Green's functions. The developed approach allowed us to take into account the influence of both intra- and interdot Coulomb interactions on carriers' spin polarization. It was shown that the presence of the insulating bands in the conductance due to the Coulomb correlations results in the emergence of spin-polarized windows (SPWs) in magnetic field leading to the high spin polarization. We demonstrated the SPWs can be effectively manipulated by gate fields and considering the hopping between central dots in both isotropic and anisotropic regimes.