Spin-Dependent Transport through the Finite Array of Quantum Dots: Spin Gun

TL;DR

This paper investigates spin-dependent electron transport through a finite quantum dot array, demonstrating how interference effects can produce nearly complete spin polarization and high conductance, effectively creating a spin gun.

Contribution

It introduces a model of a spin gun using quantum dots that achieves near-perfect spin polarization through interference effects in electron transport.

Findings

Transmission difference between singlet and triplet channels can reach a few percent for a single dot.

Interference effects in multiple dots can lead to nearly 100% spin polarization.

Device conductance can reach approximately 1 in units of e^2/πħ at certain energies.

Abstract

The problem of spin-dependent transport of electrons through a finite array of quantum dots attached to 1D quantum wire (spin gun) for various semiconductor materials is studied. The Breit-Fermi term for spin-spin interaction in the effective Hamiltonian of the device is shown to result in a dependence of transmission coefficient on the spin orientation. The difference of transmission probabilities for singlet and triplet channels can reach few percent for a single quantum dot. For several quantum dots in the array due to interference effects it can reach approximately 100% for some energy intervals. For the same energy intervals the conductance of the device reaches the value $\approx 1$ in $[e^{2}/\pi\hbar]$ units. As a result a model of the spin-gun which transforms the spin-unpolarized electron beam into completely polarized one is suggested.