Theory of magnetotransport in ferromagnetic mesoscopic devices

Natalia Lebedeva, Pekka Kuivalainen

Research output: Contribution to journalArticleScientificpeer-review

Abstract

A quantum transport theory is developed for ferromagnetic semiconductor nanostructures, where a ferromagnetic central region (FCR) is coupled to non-magnetic leads. The strong spin-spin interaction between the charge carriers and the localized magnetic electrons causes a large splitting of the energy levels between the spin-up and spin-down carriers and increases strongly the charge carrier scattering rate due to the spin disorder scattering in the FCR. The electronic structure of the FCR and the scattering rate can be estimated from the real and imaginary parts of the poles of the retarded Green's function including the spin-spin interaction. Then a quantum transport theory can be developed by using the Keldysh non-equilibrium-Green-function technique. A general expression for the transmission coefficient T(E) can be calculated by using the retarded and advanced Green functions for the FCR. Numerical results are presented for a ferromagnetic AlAs/(Ga,Mn)As/AlAs quantum well with a single resonant level coupled to the non-magnetic metallic leads by tunneling. The calculated results show that the strong spin-spin interaction leads to a shift and a broadening of the peak for T(E) as compared to the non-interacting case. Also a double peak structure due to the splitting of the resonant level is shown in the ferromagnetic temperature region.
Original languageEnglish
Pages (from-to)80 - 84
Number of pages5
JournalPhysica Scripta
VolumeT114
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

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Green's function
Quantum Transport
Transport Theory
Green's functions
transport theory
Scattering
Quantum Theory
charge carriers
scattering
Interaction
Charge
Transmission Coefficient
interactions
Electronic Structure
Quantum Well
Gallium Arsenide
Nanostructures
Energy Levels
Non-equilibrium
Pole

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Lebedeva, Natalia ; Kuivalainen, Pekka. / Theory of magnetotransport in ferromagnetic mesoscopic devices. In: Physica Scripta. 2004 ; Vol. T114. pp. 80 - 84.
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title = "Theory of magnetotransport in ferromagnetic mesoscopic devices",
abstract = "A quantum transport theory is developed for ferromagnetic semiconductor nanostructures, where a ferromagnetic central region (FCR) is coupled to non-magnetic leads. The strong spin-spin interaction between the charge carriers and the localized magnetic electrons causes a large splitting of the energy levels between the spin-up and spin-down carriers and increases strongly the charge carrier scattering rate due to the spin disorder scattering in the FCR. The electronic structure of the FCR and the scattering rate can be estimated from the real and imaginary parts of the poles of the retarded Green's function including the spin-spin interaction. Then a quantum transport theory can be developed by using the Keldysh non-equilibrium-Green-function technique. A general expression for the transmission coefficient T(E) can be calculated by using the retarded and advanced Green functions for the FCR. Numerical results are presented for a ferromagnetic AlAs/(Ga,Mn)As/AlAs quantum well with a single resonant level coupled to the non-magnetic metallic leads by tunneling. The calculated results show that the strong spin-spin interaction leads to a shift and a broadening of the peak for T(E) as compared to the non-interacting case. Also a double peak structure due to the splitting of the resonant level is shown in the ferromagnetic temperature region.",
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Theory of magnetotransport in ferromagnetic mesoscopic devices. / Lebedeva, Natalia; Kuivalainen, Pekka.

In: Physica Scripta, Vol. T114, 2004, p. 80 - 84.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Theory of magnetotransport in ferromagnetic mesoscopic devices

AU - Lebedeva, Natalia

AU - Kuivalainen, Pekka

PY - 2004

Y1 - 2004

N2 - A quantum transport theory is developed for ferromagnetic semiconductor nanostructures, where a ferromagnetic central region (FCR) is coupled to non-magnetic leads. The strong spin-spin interaction between the charge carriers and the localized magnetic electrons causes a large splitting of the energy levels between the spin-up and spin-down carriers and increases strongly the charge carrier scattering rate due to the spin disorder scattering in the FCR. The electronic structure of the FCR and the scattering rate can be estimated from the real and imaginary parts of the poles of the retarded Green's function including the spin-spin interaction. Then a quantum transport theory can be developed by using the Keldysh non-equilibrium-Green-function technique. A general expression for the transmission coefficient T(E) can be calculated by using the retarded and advanced Green functions for the FCR. Numerical results are presented for a ferromagnetic AlAs/(Ga,Mn)As/AlAs quantum well with a single resonant level coupled to the non-magnetic metallic leads by tunneling. The calculated results show that the strong spin-spin interaction leads to a shift and a broadening of the peak for T(E) as compared to the non-interacting case. Also a double peak structure due to the splitting of the resonant level is shown in the ferromagnetic temperature region.

AB - A quantum transport theory is developed for ferromagnetic semiconductor nanostructures, where a ferromagnetic central region (FCR) is coupled to non-magnetic leads. The strong spin-spin interaction between the charge carriers and the localized magnetic electrons causes a large splitting of the energy levels between the spin-up and spin-down carriers and increases strongly the charge carrier scattering rate due to the spin disorder scattering in the FCR. The electronic structure of the FCR and the scattering rate can be estimated from the real and imaginary parts of the poles of the retarded Green's function including the spin-spin interaction. Then a quantum transport theory can be developed by using the Keldysh non-equilibrium-Green-function technique. A general expression for the transmission coefficient T(E) can be calculated by using the retarded and advanced Green functions for the FCR. Numerical results are presented for a ferromagnetic AlAs/(Ga,Mn)As/AlAs quantum well with a single resonant level coupled to the non-magnetic metallic leads by tunneling. The calculated results show that the strong spin-spin interaction leads to a shift and a broadening of the peak for T(E) as compared to the non-interacting case. Also a double peak structure due to the splitting of the resonant level is shown in the ferromagnetic temperature region.

U2 - 10.1088/0031-8949/2004/T114/019

DO - 10.1088/0031-8949/2004/T114/019

M3 - Article

VL - T114

SP - 80

EP - 84

JO - Physica Scripta

JF - Physica Scripta

SN - 0031-8949

ER -