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

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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 ≈ 1 in [e²/πℏ] units. As a result a model of the spin-gun which transforms the spin-unpolarized electron beam into completely polarized one is suggested.