Thermal Enhancement of Interference Effects in Quantum Point Contacts

Abbout, Adel; Lemarié, Gabriel; Pichard, Jean‐Louis

doi:10.1103/physrevlett.106.156810

Cited by 10 publications

(33 citation statements)

References 25 publications

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“…45 When the smoothing provided by a finite temperature is large enough, the step and plateau behaviors get mixed, and nonmonotonous dependencies of the fringes appearing in the conductance corrections on temperature can be obtained. 35 …”

Section: Discussionmentioning

confidence: 99%

“…(35). Details are provided in Appendix C. The second-order correction in V T to the total current in linear response to the applied bias V is obtained by summing I …”

Section: Second-order Perturbation In the Tip Potentialmentioning

confidence: 99%

“…This explains a change in the SGM response depending on the tuning of the QPC, and is consistent with a thermal enhancement of the interference patterns proposed for a QPC tuned close to the edge of a plateau. 35 Most of the experiments performed up to date use a very strong tip-induced potential to obtain significant contrast. Such a regime most likely requires higher-order corrections to be considered or a nonperturbative approach.…”

Section: Introductionmentioning

confidence: 99%

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Theory of scanning gate microscopy

et al. 2013

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A systematic theory of the conductance measurements of noninvasive (weak probe) scanning gate microscopy is presented that provides an interpretation of what precisely is being measured. A scattering approach is used to derive explicit expressions for the first-and second-order conductance changes due to the perturbation by the tip potential in terms of the scattering states of the unperturbed structure. In the case of a quantum point contact, the first-order correction dominates at the conductance steps and vanishes on the plateaux where the second-order term dominates. Both corrections are nonlocal for a generic structure. Only in special cases, such as that of a centrally symmetric quantum point contact in the conductance quantization regime, can the second-order correction be unambiguously related with the local current density. In the case of an abrupt quantum point contact, we are able to obtain analytic expressions for the scattering eigenfunctions and thus evaluate the resulting conductance corrections.

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Section: Discussionmentioning

confidence: 99%

“…(35). Details are provided in Appendix C. The second-order correction in V T to the total current in linear response to the applied bias V is obtained by summing I …”

Section: Second-order Perturbation In the Tip Potentialmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Theory of scanning gate microscopy

et al. 2013

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“…7 Mapping of conductance of quantum point contacts (QPCs) allowed for observation of spatial maps of the coherent electron flow [8][9][10][11][12][13][14] and signatures of interference involving the presence of the tip. 15,16 Moreover it has been found that the electron current after leaving the QPC propagates in narrow branches 17,18 and that checkerboard interference patterns 19 are observed in the maps of the electron flow. 20 Recent experiments measured nonequilibrium transport phenomena in QPCs 21 and demonstrated the control of the edge channel trajectories in the quantum Hall regime.…”

Section: Introductionmentioning

confidence: 99%

“…22 Recent theoretical studies on SGM in QPC systems delivered a perturbative description 23 of the transport and a temperature-induced amplification of the interference fringes. 16 There is a growing interest in spin phenomena in twodimensional electron gas (2DEG). A particular attention is paid to spin-orbit (SO) interaction that results in an effective magnetic field for propagating electrons and allows for control of the electron spin by the electric fields.…”

Section: Introductionmentioning

confidence: 99%

Signatures of spin-orbit coupling in scanning gate conductance images of electron flow from quantum point contacts

2014

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Electron flow through a quantum point contact in presence of spin-orbit coupling is investigated theoretically in the context of the scanning gate microscopy (SGM) conductance mapping. Although in the absence of the floating gate the spin-orbit coupling does not significantly alter the conductance, we find that the angular dependence of the SGM images of the electron flow at the conductance plateaux is substantially altered as the spin-orbit interaction mixes the orbital modes that enter the quantum point contact. The radial interference fringes that are obtained in the SGM maps at conductance steps are essentially preserved by the spin-orbit interaction as backscattering by the tip preserves the electron spin although the effects of the mode mixing are visible.

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Conductance microscopy of quantum dots weakly or strongly coupled to the conducting channel

Kolasiński¹,

Szafran²

2014

New J. Phys.

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We consider scanning gate conductance microscopy of an open quantum dot that is connected to the conducting channel using the wave function description of the quantum transport and a finite difference approach. We discuss the information contained in conductance (G) maps. We demonstrate that the maps for a delta-like potential perturbation exactly reproduce the local density of states for a quantum dot that is weakly coupled to the channel, i.e. when the connection of the channel to the dot transmits a single transport mode only. We explain this finding in terms of the Lippmann-Schwinger perturbation theory. We demonstrate that the signature of the weak coupling conditions is the conductance, which for P subbands at the Fermi level varies between − P 1 and P in units of e h 2 2 . For stronger coupling of the quantum dot to the channel, the G maps resolve the local density of states only for very specific work points, with the Fermi energy coinciding with quasi-bound energy levels.Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. New J. Phys. 16 (2014) 053044 K Kolasiński and B Szafran New J. Phys. 16 (2014) 053044 K Kolasiński and B Szafran 3 New J. Phys. 16 (2014) 053044 K Kolasiński and B Szafran New J. Phys. 16 (2014) 053044 K Kolasiński and B Szafran 6 New J. Phys. 16 (2014) 053044 K Kolasiński and B Szafran 13Figure 11. Single-subband transport P = 1, for E = 4.1 meV. The probability density for the electron incident from the left (a), (c) and right (b), (d) for W = 50 nm (a), (b) and W = 80 nm (c), (d).

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Thermal Enhancement of Interference Effects in Quantum Point Contacts

Cited by 10 publications

References 25 publications

Theory of scanning gate microscopy

Theory of scanning gate microscopy

Signatures of spin-orbit coupling in scanning gate conductance images of electron flow from quantum point contacts

Conductance microscopy of quantum dots weakly or strongly coupled to the conducting channel

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