Conductance modulation of spin interferometers

Cahay, M.; Bandyopadhyay, Supriyo

doi:10.1103/physrevb.68.115316

Cited by 54 publications

(48 citation statements)

References 22 publications

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“…found a resonant spin Hall conductance in a two-dimensional (2D) system with Rashba SO interaction under a perpendicular magnetic field 6 . There are also many other works on related issues where SO interaction plays a central role 12,13,14,15,16,17 , and this research direction is expanding in a very rapid pace due to its possible application to spintronics.…”

Section: Introductionmentioning

confidence: 99%

Quantum transport theory for nanostructures with Rashba spin-orbital interaction

2005

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We report on a general theory for analyzing quantum transport through devices in the Metal-QD-Metal configuration where QD is a quantum dot or the device scattering region which contains Rashba spin-orbital and electron-electron interactions. The metal leads may or may not be ferromagnetic, they are assumed to weakly couple to the QD region. Our theory is formulated by second quantizing the Rashba spin-orbital interaction in spectral space (instead of real space), and quantum transport is then analyzed within the Keldysh nonequilibrium Green's function formalism. The Rashba interaction causes two main effects to the Hamiltonian: (i) it gives rise to an extra spin-dependent phase factor in the coupling matrix elements between the leads and the QD; (ii) it gives rise to an inter-level spin-flip term but forbids any intra-level spin-flips. Our formalism provides a starting point for analyzing many quantum transport issues where spin-orbital effects are important. As an example, we investigate transport properties of a Aharnov-Bohm ring in which a QD having Rashba spin-orbital and e-e interactions is located in one arm of the ring. A substantial spin-polarized conductance or current emerges in this device due to a combined effect of a magnetic flux and the Rashba interaction. The direction and strength of the spin-polarization are shown to be controllable by both the magnetic flux and a gate voltage.

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Section: Introductionmentioning

confidence: 99%

Quantum transport theory for nanostructures with Rashba spin-orbital interaction

2005

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“…To study various ballistic spin transport phenomena, wave function approaches [34][35][36][37]46 within the scattering matrix formalism, and Green's function techniques 30,32,33 with discrete lattices have been used in quasi-one-dimensional systems. As another way, in Ref.…”

Section: Introductionmentioning

confidence: 99%

Spin nutation and polarization in ballistic semiconductor nanostructures

Cho

2008

Phys. Rev. B

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The definitions of spin orientation and polarization vectors are introduced within the particle density matrix of scattering states in leads. It is shown that spin-density vector can be defined by the product of the spin orientation vector, being a unit direction vector, and the charge density, corresponding to the amplitude of the spin-density vector, experimentally observable by a spatial charge modulation measurement. When an electron transports through a ballistic semiconductor nanostructure, due to quantum interference of two spin eigenmodes, the electron spin generally undergoes nutation on its precession around the effective magnetic field resulting from spin-orbit interactions. The nutation of electron spin is found to be crucial for spin polarization in the quantum transport. When one of two spin-dependent channels in leads is evanescent, electron spin is shown to be fully polarized for distance from the interface larger than the spin precession length.

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“…Hereafter, we label these two configurations "ON" and "OFF" since they correspond to ON and OFF states of the transistor. Both in the ON and OFF states, T (E) contains several peaks and troughs due to Ramsauer and Fano resonances in the conductance of the channel, features which we have analyzed thoroughly in the past [6,7,8]. In the energy range [4198.5 -4200.5] meV, the transmission coefficient reaches unity several times when the SpinFET is biased in the ON configuration but is close to zero when biased in the complementary scheme.…”

Section: Resultsmentioning

confidence: 99%

“…This technique is fairly involved and the reader is referred to refs. [6,7,8] for the details. The results presented here are based on the assumption of the device parameters listed in Table I.…”

Section: Resultsmentioning

confidence: 99%

“…That results in considerable dynamic energy dissipation during switching. In contrast, our strategy is to modulate transmission resonances (Ramsauer and Fano-type resonances) that occur in the channel of traditional SpinFETs [6,7,8] with a gate potential. Since the resonance widths (in energy) are very small, a few mV change in the gate potential can take the device from on-resonance to off-resonance and switch it on or off.…”

Section: Introductionmentioning

confidence: 99%

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Proposal for a dual-gate spin field effect transistor: A device with very small switching voltage and a large ON to OFF conductance ratio

Wan

Cahay

Bandyopadhyay

2008

Physica E: Low-dimensional Systems and Nanostructures

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We propose and analyze a novel dual-gate Spin Field Effect Transistor (SpinFET) with half-metallic ferromagnetic source and drain contacts. The transistor has two gate pads that can be biased independently. It can be switched ON or OFF with a few mV change in the differential bias between the two pads, resulting in extremely low dynamic power dissipation during switching. The ratio of ON to OFF conductance remains fairly large (∼ 60) up to a temperature of 10 K. This device also has excellent inverter characteristics, making it attractive for applications in low power and high density Boolean logic circuits.

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Conductance modulation of spin interferometers

Cited by 54 publications

References 22 publications

Quantum transport theory for nanostructures with Rashba spin-orbital interaction

Quantum transport theory for nanostructures with Rashba spin-orbital interaction

Spin nutation and polarization in ballistic semiconductor nanostructures

Proposal for a dual-gate spin field effect transistor: A device with very small switching voltage and a large ON to OFF conductance ratio

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