A direct measurement of the effects of Fermi energy oscillations in quasi-1D systems

Macks, L. D.; Barnes, Colin; Nicholls, J.E.; Tribe, W. R.; Ritchie, D. A.; Rose, P. D.; Linfield, E. H.; Pepper, M.

doi:10.1016/s1386-9477(99)00098-3

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…There is also a plateau near Gϭ0. 35, as expected from this analysis for G 0.35 , but the height does not appear to change with G 0.7 , and it also varies with V sd . It is thus difficult to know which value to take when comparing with G 0.7 .…”

Section: Modelssupporting

confidence: 81%

“…The latter is pinned just below the chemical potential due to its large density of states. 35 As the chemical potential drops, the spin splitting is assumed to decrease, so that the two subbands merge just as they become completely depopulated. This is a many-body ground state, in which the system minimizes its total energy by having different occupations of the two spinsplit subbands.…”

Section: Modelsmentioning

confidence: 99%

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Spin splitting of one-dimensional subbands in high quality quantum wires at zero magnetic field

et al. 2000

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We have studied the transport properties of a high quality one-dimensional constriction formed in an undoped GaAs/Al x Ga 1Ϫx As heterostructure and therefore largely free of the random potential of ionized donors. We induce an electron gas electrostatically and are able to vary the sheet carrier density (n 2D ) by a factor of at least seven. The constriction shows resonance-free integer conductance plateaus and the additional ''0.7 structure,'' a plateaulike feature, the conductance of which decreases from about 0.80 towards 0.5 ϫ2e 2 /h at low and high n 2D . This low value is unaffected by a high in-plane magnetic field, supporting previous evidence and theories that the breaking of the spin degeneracy at high fields persists in some form, even at zero field. The height of the feature generally seen at a conductance of about 0.85ϫ2e 2 /h at high dc bias also varies, and we show that this is in reasonable agreement with a simple relation linking the conductances of the two features. We use a source-drain bias to study the spin splitting of the lowest one-dimensional subbands, and find a spin gap that is independent of n 2D for the first subband. We discuss possible reasons for the splitting, and show how various models for the 0.7 structure can be applied in the finite bias regime.

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Section: Modelssupporting

confidence: 81%

Section: Modelsmentioning

confidence: 99%

Spin splitting of one-dimensional subbands in high quality quantum wires at zero magnetic field

et al. 2000

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“…4, would manifest themselves as variations in the current across the QPC as the magnetic field is varied [26]. Additionally, the tunneling of electrons from a quasione-dimensional wire into an adjacent two-dimensional electron system would contain signatures of the highfrequency transverse momentum components contained within the density modulations observed in this paper [27,28] as well as other correlation and many-particle effects [29][30][31].…”

Section: Discussionmentioning

confidence: 76%

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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“…͑1͒ it is not appropriate to substitute ‫ץ‬G/‫ץ‬E by ‫ץ‬G/‫ץ‬V g . As a 1D subband is populated there is a tendency for the subband edge to become pinned to the chemical potential, because of the singularity in the 1D density of states D(E); this has been demonstrated in 1D-2D tunneling, 16 in DC voltage biased conductance measurements, 13 and in capacitance. 17 Although the ob- served plateaus in conductance and thermopower suggest that such a locking of the Fermi energy may indeed be responsible for the 0.7 structure, the behavior of the conductance with temperature and magnetic field are not easily reconciled with such a model and this may provide a clue to the underlying mechanism.…”

Section: Fig 1 Simultaneous Measurements Of Thermopower and Con-mentioning

confidence: 99%

Direction-resolved transport and possible many-body effects in one-dimensional thermopower

et al. 2000

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A single-particle theory due to Mott predicts a proportionality between the diffusion thermopower and the energy derivative of the logarithm of the conductance. Measurements of a ballistic 1D wire show that the Mott theory remains valid in the presence of a finite current, and that it leads to a direction-sensitive probe of electron transport. We observe an apparent violation of the Mott model at low electron densities, when there is a nonquantized plateau in the conductance at 0.7(2e 2 /h). There is as yet no successful theoretical explanation of this so called 0.7 structure, but the distinctive thermopower signature, which deviates from single-particle predictions, may provide the key to a better understanding.

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A direct measurement of the effects of Fermi energy oscillations in quasi-1D systems

Cited by 6 publications

References 5 publications

Spin splitting of one-dimensional subbands in high quality quantum wires at zero magnetic field

Spin splitting of one-dimensional subbands in high quality quantum wires at zero magnetic field

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

Direction-resolved transport and possible many-body effects in one-dimensional thermopower

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