Spin-filter modeling by means of extension theory methods

TL;DR

This paper models spin-dependent electron transport through quantum dot arrays using extension theory methods, revealing energy-dependent interactions that can fully polarize unpolarized electron beams.

Contribution

It introduces a novel extension theory-based model for quantum dots with internal structures, enabling analysis of spin filtering effects in quantum wire systems.

Findings

Transmission probability differences can reach 100% for certain energies.

Device conductance can reach quantized units.

Model predicts complete polarization of unpolarized electron beams.

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. Unlike the model considered in [1] a model proposed here is based on the extension theory model (ETM) and assumes the quantum dots to have an arbitrary internal structure, i.e. the internal energy levels. The presence of internal structure in quantum dots results in energy-dependent interaction between electrons and quantum dots. This interaction changes the transmission mode of the spin current through the spin gun. For the energy-dependent interaction it is shown in this article the difference of transmission probabilities for singlet and triplet channels for several quantum dots in the array due to interference effects can reach approximately 100% percent for some energy intervals. For the same energy intervals the conductance of the device reaches the value in units. As a result a model of the spin-gun which transforms the spin unpolarized electron beam into completely polarized one is suggested.