On-demand large-conductance in trivial zero-bias tunneling peaks in Majorana nanowires

Abstract

Motivated by recent experiments that report the almost-generic large-conductance peaks without very extensive fine-tuning, we propose an alternative mechanism through direct theoretical simulations that can explain the large zero-bias conductance peaks being generated on-demand in the nontopological regime in Majorana nanowires by satisfying the following three sufficient conditions: (i) strong potential disorder in the bulk of the nanowire, suppressing the topological regime; (ii) strong suppression of the disorder near the nanowire ends connecting to the tunneling leads, perhaps because of screening by the metallic leads and gates; and (iii) low tunnel barrier strength leading to large tunneling amplitude. The third condition is typically achieved experimentally by fine-tuning the tunnel barrier and the first condition is generic in all existing nanowires by virtue of considerable sample disorder induced by unintentional random quenched charged impurities. The second condition is likely to apply to many samples since the disorder potential would be typically screened more strongly at the wire ends because of the large metallic tunnel pads used experimentally. We show that the resultant tunneling conductance manifests large trivial zero-bias peaks almost on demand, and such peaks could be $\sim 2e^2/h$, when appropriately fine-tuned by the tunnel barrier strength and the temperature, as reported experimentally. Our work not only solves the mystery in recent experiments that the observations of the large zero-bias conductance peaks are generic by proposing a theoretically possible mechanism but also explains why these hypothesized conditions are naturally satisfied in experiments.

8 pages, 5 figures

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• Density of states, transport, and topology in disordered Majorana nanowires
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• Random matrix theory for the robustness, quantization, and end-to-end correlation of zero-bias conductance peaks in a class D ensemble
• Probing Majorana bound states through an inhomogeneous Andreev double dot interferometer
• InP/GaSb core-shell nanowires: a novel hole-based platform with strong spin-orbit coupling for full-shell hybrid devices
• Quantum spin Hall insulator in proximity with a superconductor: Transition to the Fulde-Ferrell-Larkin-Ovchinnikov state driven by a Zeeman field
• Topological phases in the presence of disorder and longer-range couplings
• Majorana zero modes in semiconductor-superconductor hybrid structures: Defining topology in short and disordered nanowires through Majorana splitting
• Multiple Majorana bound states and their resilience against disorder in planar Josephson junctions
• Magnetic field-free braiding and nontrivial fusion of Majorana bound states in high-temperature planar Josephson junctions
• Dominant superconducting correlations in a Luttinger liquid induced by spin fluctuations