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  4. Origin of Subgap States in Normal-Insulator-Superconductor van der Waals Heterostructures
 
research article

Origin of Subgap States in Normal-Insulator-Superconductor van der Waals Heterostructures

Karnatak, Paritosh
•
Mingazheva, Zarina
•
Watanabe, Kenji
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March 16, 2023
Nano Letters

Superconductivity in van der Waals materials, such as NbSe2 and TaS2, is fundamentally novel due to the effects of dimensionality, crystal symmetries, and strong spin-orbit coupling. In this work, we perform tunnel spectroscopy on NbSe2 by utilizing MoS2 or hexagonal boron nitride (hBN) as a tunnel barrier. We observe subgap excitations and probe their origin by studying various heterostructure designs. We show that the edge of NbSe2 hosts many defect states, which strongly couple to the superconductor and form Andreev bound states. Furthermore, by isolating the NbSe2 edge we show that the subgap states are ubiquitous in MoS2 tunnel barriers but absent in hBN tunnel barriers, suggesting defects in MoS2 as their origin. Their magnetic nature reveals a singlet- or a doublet-type ground state, and based on nearly vanishing g factors or avoided crossings of subgap excitations, we highlight the role of strong spin-orbit coupling.

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Type
research article
DOI
10.1021/acs.nanolett.2c02777
Web of Science ID

WOS:000954976700001

Author(s)
Karnatak, Paritosh
Mingazheva, Zarina
Watanabe, Kenji
Taniguchi, Takashi
Berger, Helmuth  
Forro, Laszlo  
Schoenenberger, Christian
Date Issued

2023-03-16

Publisher

AMER CHEMICAL SOC

Published in
Nano Letters
Subjects

Chemistry, Multidisciplinary

•

Chemistry, Physical

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Nanoscience & Nanotechnology

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Materials Science, Multidisciplinary

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Physics, Applied

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Physics, Condensed Matter

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Chemistry

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Science & Technology - Other Topics

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Materials Science

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Physics

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nbse 2

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superconductivity

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nanostructures

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andreev bound state

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subgap excitation

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tunneling

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defect

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transport

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nbse2

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

Available on Infoscience
April 24, 2023
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/197121
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