Conductance smearing and anisotropic suppression of induced superconductivity in a Majorana nanowire

Chun-Xiao Liu, Jay D. Sau, Tudor D. Stanescu, and S. Das Sarma
Phys. Rev. B 99, 024510 – Published 22 January 2019

Abstract

In a recent high-quality experimental work on normal metal–superconducting nanowire junctions (J. D. S. Bommer et al., arXiv:1807.01940), strong anisotropic suppression of induced superconductivity has been observed in tunnel conductance measurements in the presence of applied magnetic field with variable orientation. Following this finding, we investigate theoretically the dependence of tunnel conductance on the direction of the Zeeman field in order to understand the operational mechanisms and to extract effective system parameters. Second, motivated by a generic discrepancy between experiment and theory, i.e., many in-gap and above-gap conductance features predicted by theory are barely observed in experiments, we study several mechanisms possibly responsible for the suppression of the theoretically predicted conductance features (e.g., length of the nanowire, self-energy effect due to the proximity effect, finite temperature, finite dissipation, and multiband effect). One essential finding in the current work is that only by a combined understanding of both suppression mechanisms can we extract effective system parameters from the experimental data (e.g., the effective nanowire-superconductor coupling, the effective Landé g factor, and the chemical potential of the semiconducting nanowire). In addition, we consider topologically trivial Andreev bound states in hybrid nanowires in the presence of potential inhomogeneities, such as external quantum dots or potential inhomogeneities inside the nanowire. We compare the anisotropic, field-dependent features induced by these nontopological Andreev bound states with the corresponding features produced by topological Majorana zero modes in pristine nanostructures, so that we can provide guidance to differentiate between the topologically trivial and nontrivial cases.

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  • Received 28 November 2018
  • Revised 23 December 2018

DOI:https://doi.org/10.1103/PhysRevB.99.024510

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Chun-Xiao Liu1, Jay D. Sau1, Tudor D. Stanescu1,2, and S. Das Sarma1

  • 1Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
  • 2Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA

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Issue

Vol. 99, Iss. 2 — 1 January 2019

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