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Quantized and unquantized zero-bias tunneling conductance peaks in Majorana nanowires: Conductance below and above 2e(2)/h

TitleQuantized and unquantized zero-bias tunneling conductance peaks in Majorana nanowires: Conductance below and above 2e(2)/h
Publication TypeJournal Article
Year of Publication2021
AuthorsH. Pan, C-X. Liu, M. Wimmer, and S. Das Sarma
JournalPhys. Rev. B
Volume103
Date PublishedJUN 1
Type of ArticleArticle
ISSN2469-9950
Abstract

Majorana zero modes can appear at the wire ends of a one-dimensional topological superconductor and manifest themselves as a quantized zero-bias conductance peak in the tunneling spectroscopy of normal-superconductor junctions. However, in superconductor-semiconductor hybrid nanowires, zero-bias conductance peaks may arise owing to topologically trivial mechanisms as well, mimicking the Majorana-induced topological peak in many aspects. In this work, we systematically investigate the characteristics of zero-bias conductance peaks for topological Majorana bound states, trivial quasi-Majorana bound states and low-energy Andreev bound states arising from smooth potential variations and disorder-induced subgap bound states. Our focus is on the conductance peak value (i.e., equal to, greater than, or less than 2e(2)/h), as well as the robustness (plateau- or spike-like) against the tuning parameters (e.g., the magnetic field and tunneling gate voltage) for zero-bias peaks arising from the different mechanisms. We find that for Majoranas and quasi-Majoranas, the zero-bias peak values are no more than 2e(2)/h, and a quantized conductance plateau forms generically as a function of parameters. By contrast, for conductance peaks due to low-energy Andreev bound states or disorder-induced bound states, the peak values may exceed 2e(2)/h, and a conductance plateau is rarely observed unless through careful postselection and fine-tuning. Our findings should shed light on the interpretation of experimental measurements on the tunneling spectroscopy of normal-superconductor junctions of hybrid Majorana nanowires.

DOI10.1103/PhysRevB.103.214502