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

Paritosh Karnatak; Zarina Mingazheva; Kenji Watanabe; Takashi Taniguchi; Helmuth Berger; László Forró; Christian Schönenberger

doi:10.1021/acs.nanolett.2c02777

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

Paritosh Karnatak ; Zarina Mingazheva ; Kenji Watanabe (National Institute for Materials Science) ; Takashi Taniguchi (National Institute for Materials Science) ; Helmuth Berger ; László Forró ; Christian Schönenberger

Download file (5.17MB)
Download as zip (4.84MB)

コレクション

引用

Paritosh Karnatak, Zarina Mingazheva, Kenji Watanabe, Takashi Taniguchi, Helmuth Berger, László Forró, Christian Schönenberger. Origin of Subgap States in Normal-Insulator-Superconductor van der Waals Heterostructures. Nano Letters. 2023, 23 (7), 2454-2459. https://doi.org/10.1021/acs.nanolett.2c02777

(BibTeX)

説明:

(abstract)

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-crossing of subgap excitations we highlight the role of strong spin-orbit coupling.

権利情報: