Spin tunneling through an indirect barrier: Tight-binding calculations

Sandu, Titus; Chantis, A. N.; Iftimie, Radu

doi:10.1103/physrevb.73.075313

Cited by 18 publications

(17 citation statements)

References 31 publications

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“…In the 3D case, such calculations were recently carried out for some specific materials and qualitatively new features were found. 14,15,16 2D tunnel structures are scantily studied to date. In particular, as far as we know, even the complex band structure of 2D electrons was not explored.…”

Section: Introductionmentioning

confidence: 99%

Evanescent states in two-dimensional electron systems with spin-orbit interaction and spin-dependent transmission through a barrier

Sablikov

Tkach

2007

Phys. Rev. B

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We find that the total spectrum of electron states in a bounded 2D electron gas with spin-orbit interaction contains two types of evanescent states lying in different energy ranges. The first-type states fill in a gap, which opens in the band of propagating spin-splitted states if tangential momentum is nonzero. They are described by a pure imaginary wavevector. The states of second type lie in the forbidden band. They are described by a complex wavevector. These states give rise to unusual features of the electron transmission through a lateral potential barrier with spin-orbit interaction, such as an oscillatory dependence of the tunneling coefficient on the barrier width and electron energy. But of most interest is the spin polarization of an unpolarized incident electron flow. Particularly, the transmitted electron current acquires spin polarization even if the distribution function of incident electrons is symmetric with respect to the transverse momentum. The polarization efficiency is an oscillatory function of the barrier width. Spin filtering is most effective, if the Fermi energy is close to the barrier height.

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Section: Introductionmentioning

confidence: 99%

Evanescent states in two-dimensional electron systems with spin-orbit interaction and spin-dependent transmission through a barrier

Sablikov

Tkach

2007

Phys. Rev. B

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“…[41][42][43][44] Such sharp dips (antiresonance states) are specific to the interferometric nature of the scattering and do not occur in conventional one-dimensional scattering problems of potential barriers. This may be due to the interference between two channels.…”

Section: Calculated Results and Discussionmentioning

confidence: 99%

Topology effects of interface and gate voltage on electrical transport through the CNT/C60/CNT junction using the Green’s function method

Shokri

Nikzad

2011

Journal of Applied Physics

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PAMELA: An open-source software package for calculating nonlocal exact exchange effects on electron gases in core-shell nanowires AIP Advances 2, 032173 (2012) Tunable electronic transport characteristics through an AA-stacked bilayer graphene with magnetoelectric barriers J. Appl. Phys. 112, 053714 (2012) Pinned interface dipole-induced tunneling electroresistance in ferroelectric tunnel junctions: A theoretical investigation J. Appl. Phys. 112, 054104 (2012) Current-voltage characteristics and ON/OFF ratio in ferroelectric tunnel junctions J. Appl. Phys. 112, 054102 (2012) Observation of fluctuation-induced tunneling conduction in micrometer-sized tunnel junctions AIP Advances 2, 032155 (2012) Additional information on J. Appl. Phys.In this work, we investigate electron transport across a carbon molecular junction consisting of a C 60 molecule attached to two semi-infinite metallic open-end CNT leads in the coherent regime.Here, we put emphasis on topology of the molecular-electrode interface and gate voltage, and obtain the electrical transmission through the CNT/C 60 /CNT structure, using the Green's function method in the framework of a nearest neighbor tight-binding approximation. To this end, three different ways of coupling C 60 fullerene through one, five, and six carbon atoms to the CNT-leads in the direction of the longitudinal axis of the tube have been considered. Also, the current-voltage characteristic is calculated in the Landauer-Büttiker formalism at room temperature. It is shown that the number of contact points between the electrodes and the molecule can play an important role in the electrical transport. Also, the bond dimerization and a gate voltage shift the molecular levels, where by adjusting the related parameters the electron conduction can be controlled. Our results show that the proposed structure gives rise to the resonance states and quasi-bound states (Fano resonances) close to À2.63 eV. These antiresonance states are related to the active region and independent from the coupling strength between the device and the leads. The numerical results may serve as important components of nanocircuits.

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“…In their work, the authors considered the electrons close to the top of the indirect barrier, where the indirect tunneling becomes dominant [2]. In our previous work [3] we have shown that, at these energies, the Γ-X mixing plays a greater role than Mishra et al suggested [2]. We have also considered the Fano resonances that occur because of the interaction between the discrete states at the X point in the barrier and the continuum at the Γ point in the contacts.…”

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confidence: 99%

“…The zero in the transmission occurs whenever the amplitude magnitudes of the two channels become equal. In our previous paper [3] we have used a realistic empirical tight binding model to give a unified description of the spin dependent tunneling through an indirect symmetric barrier with the GaAs/AlAs/GaAs heterostructure as an example. We showed several interesting aspects of such process, with particular emphasis on the large energy windows of spin polarization that can be obtained when appropriate conditions are satisfied.…”

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confidence: 99%

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Ab-initiocalculations of spin tunneling through an indirect barrier

Chantis

Sandu

2008

PMC Phys B

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We use a fully relativistic layer Green's functions approach to investigate spin-dependent tunneling through a symmetric indirect band gap barrier like GaAs/AlAs/GaAs heterostructure along [100] direction. The method is based on Linear Muffin Tin Orbitals and it is within the Density Functional Theory (DFT) in the Local Density Approximation (LDA). We find that the results of our ab-initio calculations are in good agreement with the predictions of our previous empirical tight binding model [Phys. Rev. B, 075313 (2006)]. In addition we show the k || -dependence of the spin polarization which we did not previously include in the model. The ab-initio calculations indicate a strong k || -dependence of the transmission and the spin polarization due to band non-parabolicity. A large window of 25-50% spin polarization was found for a barrier of 8 AlAs monolayers at k || = 0.03 2π/ a. Our calculations show clearly that the appearance of energy windows with significant spin polarization depends mostly on the location of transmission resonances and their corresponding zeros and not on the magnitude of the spin splitting in the barrier.

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Spin tunneling through an indirect barrier: Tight-binding calculations

Cited by 18 publications

References 31 publications

Evanescent states in two-dimensional electron systems with spin-orbit interaction and spin-dependent transmission through a barrier

Evanescent states in two-dimensional electron systems with spin-orbit interaction and spin-dependent transmission through a barrier

Topology effects of interface and gate voltage on electrical transport through the CNT/C60/CNT junction using the Green’s function method

Ab-initiocalculations of spin tunneling through an indirect barrier

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