Suppression of scattering in quantum confined 2D helical Dirac systems

Abstract : Transport properties of helical Dirac fermions in disordered quantum wires are investigated in the large energy limit. In the quasiballistic regime, the conductance and the Fano factor are sensitive to disorder only when the Fermi energy is close to an opening of a transverse mode. In the limit of a large number of transverse modes, transport properties are insensitive to the geometry of the nanowire or the nature and strength of the disorder but, instead, are dominated by the properties of the interface between the ohmic contact and the nanowire. In the case of a heavily doped Dirac metallic contact, the conductance is proportional to the energy with an average transmission $\tau = \pi$/4 and a Fano factor of $F \simeq$ 0.13. Those results can be generalized to a much broader class of contacts, the exact values of $\tau$ and $F$ depending on the model used for the contacts. The energy dependence of Aharonov-Bohm oscillations is determined, revealing a damped oscillatory behavior and phase shifts due to the one-dimensional subband quantization and which are not the signature of the nontrivial topology.
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Contributor : Romain Giraud <>
Submitted on : Thursday, April 11, 2019 - 4:09:46 PM
Last modification on : Monday, May 6, 2019 - 10:08:13 AM

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J. Dufouleur, E. Xypakis, B. Buchner, Romain Giraud, J. Bardarson. Suppression of scattering in quantum confined 2D helical Dirac systems. Physical Review B : Condensed matter and materials physics, American Physical Society, 2018, 97 (7), pp.075401. ⟨10.1103/PhysRevB.97.075401⟩. ⟨hal-02051524⟩

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