Conductance fluctuations in mesoscopic quantum wires near the ballistic regime

Higurashi, Hitoshi; Iwahuchi, Shuichi; Nagaoka, Yosuke

doi:10.1016/0039-6028(92)90373-e

Cited by 22 publications

(8 citation statements)

References 8 publications

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“…Similar results were found for Dirac fermions in presence of a strong long-range disorder and without quantum confinement, and deviations from a universal value were only found near the ballistic regime48. In presence of quantum confinement, although reduced or enhanced conductance fluctuations can occur for a ballistic conductor with a small number of quantized modes4950515253, universality is restored even by a small disorder if the number of transverse modes exceeds a few units54. In the long Bi 2 Se 3 and Bi 2 Te 3 quantum wires studied here, both conditions L φ > L ≥ l tr ≫ l e and G ≫ e 2 / h (number of populated transverse modes N ≫ 1) should therefore set the system in the universal regime.…”

Section: Discussionsupporting

confidence: 76%

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires

Dufouleur

Veyrat

Dassonneville

et al. 2017

Sci Rep

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Disorder remains a key limitation in the search for robust signatures of topological superconductivity in condensed matter. Whereas clean semiconducting quantum wires gave promising results discussed in terms of Majorana bound states, disorder makes the interpretation more complex. Quantum wires of 3D topological insulators offer a serious alternative due to their perfectly-transmitted mode. An important aspect to consider is the mixing of quasi-1D surface modes due to the strong degree of disorder typical for such materials. Here, we reveal that the energy broadening γ of such modes is much smaller than their energy spacing Δ, an unusual result for highly-disordered mesoscopic nanostructures. This is evidenced by non-universal conductance fluctuations in highly-doped and disordered Bi2Se3 and Bi2Te3 nanowires. Theory shows that such a unique behavior is specific to spin-helical Dirac fermions with strong quantum confinement, which retain ballistic properties over an unusually large energy scale due to their spin texture. Our result confirms their potential to investigate topological superconductivity without ambiguity despite strong disorder.

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Section: Discussionsupporting

confidence: 76%

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires

Dufouleur

Veyrat

Dassonneville

et al. 2017

Sci Rep

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“…The existence of non-universal conductance fluctuations in a diffusive conductor is at odds with standard theories for massive quasi-particles [2][3][4] and for Dirac fermions [25,26], which predict universal values of δG in the fully-coherent diffusive regime. Although reduced or enhanced conductance fluctuations can occur for a ballistic conductor with a small number of quantized modes [5,[27][28][29], universality is restored even by a small disorder if the number of transverse modes exceeds a few units [30]. Similar results were found for Dirac fermions in presence of a strong long-range disorder and without quantum confinement [31].…”

Section: B) A)mentioning

confidence: 67%

Pseudo-ballistic transport in 3D topological insulator quantum wires

Dufouleur,

Veyrat,

Xypakis

et al. 2015

Preprint

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Quantum conductance fluctuations are investigated in disordered 3D topological insulator quantum wires. Both experiments and theory reveal a new transport regime in a mesoscopic conductor, pseudo-ballistic transport, for which ballistic properties persist beyond the transport mean free path, characteristic of diffusive transport. It results in non-universal conductance fluctuations due to quasi-1D surface modes, as observed in long and narrow Bi2Se3 nanoribbons. Spin helical Dirac fermions in quantum wires retain pseudo-ballistic properties over an unusually broad energy range, due to strong quantum confinement and weak momentum scattering.

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“…Recent numerical work includes studies of the density of states and of the localization lengths in such wires, 2,3 of the effect of disorder directly on the conductance and on the conductance quantization effect, 4 and of conductance fluctuations. 5,6 The present paper is a report of calculations of the zerotemperature elastic ͑phonon-free͒ resistance of fully threedimensional disordered quantum wires, with cross sections as large as 14ϫ14 atoms and lengths of up to hundreds of atoms. The calculations employ a 1s tight-binding model 7 and are based on an exact single-particle scattering theory formulation of the elastic transport problem, presented and discussed elsewhere.…”

Section: Introductionmentioning

confidence: 99%

Calculation of the residual resistivity of three-dimensional quantum wires

1996

Phys. Rev. B

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An exact scattering theory formulation of the elastic transport problem is used in a 1s tight-binding implementation to calculate the zero-temperature elastic resistances of disordered three-dimensional quantum wires with cross sections as large as 14ϫ14 atoms and lengths of up to hundreds of atoms. A real-space Green function technique is used to construct the wires. The technique is flexible and simple to implement, making it possible to study a range of different geometries, types of disorder, and combinations thereof. The possible use of such calculations to evaluate the bulk residual resistivity of the respective materials is outlined. Attention is given to the statistics and the configurational averaging of the calculated results. The transition from the Ohmic to the localization regime in the wires is also studied. The shape of this transition, obtained from the numerical results, is found to correspond well to a curious semiempirical analytic form. Model calculations with different types of on-site disorder, and with interfacial roughness, combined with impurity scattering, are presented at

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Conductance fluctuations in mesoscopic quantum wires near the ballistic regime

Cited by 22 publications

References 8 publications

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires

Pseudo-ballistic transport in 3D topological insulator quantum wires

Calculation of the residual resistivity of three-dimensional quantum wires

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