Abstract
Macroscopic superconductivity in various ultrathin films at the ultimate two-dimensional limit, i.e., films with thickness of only one- or two-atomic layers supported by single-crystal surfaces, has manifested itself in experiments with only zero resistance but not yet with the Meissner effect due to the lack of a proper in situ technique, although both phenomena are the defining characteristics of a superconductor. Using a self-developed multifunctional scanning tunneling microscope, we succeeded in detecting not only the macroscopic supercurrent but also diamagnetic response of a two-atomic-layer indium film on a Si(111) surface. The diamagnetic measurements reveal that the low-temperature variation of penetration depth follows the Bardeen-Cooper-Schrieffer theory in the dirty limit. The magnitude of the pair-breaking interaction is determined to be 0.80 from the magnetic field dependence of the zero-temperature penetration depth, which implies that the pairing symmetry deviates slightly from an isotropic wave. The present work demonstrates that it is possible to observe the Meissner effect in ultrathin superconducting films that are vulnerable to air, which is very helpful for a detailed understanding of the microscopic pairing mechanism.
- Received 23 January 2019
- Revised 9 March 2019
DOI:https://doi.org/10.1103/PhysRevB.99.140506
©2019 American Physical Society
Physics Subject Headings (PhySH)
Synopsis
An Airless Test for 2D Superconductors
Published 18 April 2019
Researchers repurpose a scanning tunneling microscope to measure the Meissner effect in 2D films kept under vacuum, allowing for confirmation of superconductivity.
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