Ground state structure and conductivity of quantum wires of infinite length and finite width

Malet, Francesc; Pí, M.; Barranco, M.; Lipparini, E.

doi:10.1103/physrevb.72.205326

Cited by 12 publications

(3 citation statements)

References 53 publications

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“…For large densities, the electrons effective screen themselves but in the LDA calculations, as they are depleted from the wire, the modulations in the transverse density distribution appear. The density modulations observed here are qualitatively different from those observed in the papers by Laux et al [2] and Malet et al [23] as they are produced exclusively by the exchange-correlation potential.…”

Section: Electron Densities In the Low-density Weak-confinement Regimecontrasting

confidence: 97%

Ground-State Electronic Structure of Quasi-One-Dimensional Wires in Semiconductor Heterostructures

Owen

Barnes

2016

Phys. Rev. Applied

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We apply density functional theory, in the local density approximation, to a quasi-one-dimensional electron gas in order to quantify the effect of Coulomb and correlation effects in modulating, and therefore patterning, the charge density distribution. Our calculations are presented specifically for surface-gate-defined quasi-one-dimensional quantum wires in a GaAs-AlGaAs heterostructure but we expect our results to apply more generally for other low dimensional semiconductor systems. We show that at high densities with strong confinement, screening of electrons in the direction transverse to the wire is efficient and density modulations are not visible. In the low-density, weak-confinement regime, the exchange-correlation potential induces small density modulations as the electrons are depleted from the wire. At the weakest confinements and lowest densities, the electron density splits into two rows thereby forming a pair of quantum wires that lie beneath the surface gates. An additional double-well external potential forms at very low density which enhances this row splitting phenomenon. We produce phase diagrams that show a transition between the presence of a single quantum wire in a split-gate structure and two quantum wires. We suggest that this phenomenon can be used to pattern and modulate the electron density in low-dimensional structures with particular application to systems where a proximity effect from a surface gate would be valuable. arXiv:1509.02457v3 [cond-mat.mes-hall]

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Section: Electron Densities In the Low-density Weak-confinement Regimecontrasting

confidence: 97%

Ground-State Electronic Structure of Quasi-One-Dimensional Wires in Semiconductor Heterostructures

Owen

Barnes

2016

Phys. Rev. Applied

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“…We express our results in terms of ρ 1D l 0 , which is the dimensionless form of the one-dimensional electron density (ρ 1D ) across the wire and corresponding to densities in the range of 5 × 10 6 -2 × 10 8 m −1 . [38] 3…”

Section: Spin Orientationmentioning

confidence: 99%

Spin texturing in a parabolically confined quantum wire with Rashba and Dresselhaus spin—orbit interactions

et al. 2014

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In this study, we investigate theoretically the effect of spin-orbit coupling on the energy level spectrum and spin texturing of a quantum wire with a parabolic confining potential subjected to the perpendicular magnetic field. Highly accurate numerical calculations have been carried out using a finite element method. Our results reveal that the interplay between the spin-orbit interaction and the effective magnetic field significantly modifies the band structure, producing additional subband extrema and energy gaps. Competing effects between external field and spin-orbit interactions introduce complex features in spin texturing owing to the couplings in energy subbands. We obtain that spatial modulation of the spin density along the wire width can be considerably modified by the spin-orbit coupling strength, magnetic field and charge carrier concentration.

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“…Exact diagonalization within the molecular subspace has been combined with rate equations to calculate tunneling currents to first order in the lead-molecule coupling strength 20 . The linear response conductance of jellium quantum point contacts has been addressed on the basis of the Kubo formula 21,22 . Although this method is restricted to the low bias regime, it has the advantage over the NEGF method that interactions outside the device region can be naturally included.…”

Section: Introductionmentioning

confidence: 99%

Conserving GW scheme for nonequilibrium quantum transport in molecular contacts

Thygesen,

Rubio

2007

Preprint

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We give a detailed presentation of our recent scheme to include correlation effects in molecular transport calculations using the non-equilibrium Keldysh formalism. The scheme is general and can be used with any quasiparticle self-energy, but for practical reasons we mainly specialize to the so-called GW self-energy, widely used to describe the quasiparticle band structures and spectroscopic properties of extended and low-dimensional systems. We restrict the GW self-energy to the central region, and describe the leads by density functional theory (DFT). A minimal basis of maximally localized Wannier functions is applied both in the central GW region and the leads. The importance of using a conserving, i.e. fully self-consistent, GW self-energy is demonstrated both analytically and by numerical examples. We introduce an effective spin-dependent interaction which automatically reduces self-interaction errors to all orders in the interaction. The scheme is applied to the Anderson model in-and out of equilibrium. In equilibrium at zero temperature we find that GW describes the Kondo resonance fairly well for intermediate interaction strengths. Out of equilibrium we demonstrate that the oneshot G0W0 approximation can produce severe errors, in particular at high bias. Finally, we consider a benzene molecule between featureless leads. It is found that the molecule's HOMO-LUMO gap as calculated in GW is significantly reduced as the coupling to the leads is increased, reflecting the more efficient screening in the strongly coupled junction. For the IV characteristics of the junction we find that HF and G0W0[GHF] yield results closer to GW than does DFT and G0W0[GDFT]. This is explained in terms of self-interaction effects and life-time reduction due to electron-electron interactions.

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Ground state structure and conductivity of quantum wires of infinite length and finite width

Cited by 12 publications

References 53 publications

Ground-State Electronic Structure of Quasi-One-Dimensional Wires in Semiconductor Heterostructures

Ground-State Electronic Structure of Quasi-One-Dimensional Wires in Semiconductor Heterostructures

Spin texturing in a parabolically confined quantum wire with Rashba and Dresselhaus spin—orbit interactions

Conserving GW scheme for nonequilibrium quantum transport in molecular contacts

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