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Super­con­duct­ing diode with­out mag­netic field in mul­ti­layer graphene

Date:
August 17, 2022
Source:
University of Innsbruck
Summary:
Superconductors are the key to lossless current flow. However, the realization of superconducting diodes has only recently become an important topic of fundamental research. An international research team has now succeeded in reaching a milestone: the demonstration of an extremely strong superconducting diode effect in a single two-dimensional superconductor.
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Superconductors are the key to lossless current flow. However, the realization of superconducting diodes has only recently become an important topic of fundamental research. An international research team involving the theoretical physicist Mathias Scheurer has now succeeded in reaching a milestone: the demonstration of an extremely strong superconducting diode effect in a single two-dimensional superconductor. They report on this in Nature Physics.

One speaks of a superconducting diode effect when there is a magnitude of the current for which a material behaves like a superconductor in one direction of current flow and like a resistor in the other. In contrast to a conventional diode, such a superconducting diode exhibits a completely vanishing resistance and thus no losses in the forward direction. This could form the basis for future lossless quantum electronics. Physicists succeeded in creating the diode effect about two years ago, but with some fundamental limitations.

The new experiments carried out in the group of Jia Li at the renowned U.S. Brown University, described in the current issue of Nature Physics, feature an extremely strong diode effect: when turning on an electrical current in one direction, the system almost immediately becomes a resistor while it stays superconducting for currents in the opposite direction. Moreover, the diode direction can be reversed by a simple electric field. "This alone makes trilayer graphene such a promising platform for the superconducting diode effect," clarifies Mathias Scheurer from the Institute of Theoretical Physics at the University of Innsbruck, who received an ERC Starting Grant this year for his research on two-dimensional materials, especially graphene. In addition, the system realizes the unique situation of a diode effect at zero external magnetic field in a single, homogeneous superconductor. This confirms a hypothesis previously theorized by Mathias Scheurer: Namely, that superconductivity and magnetism coexist in a system consisting of three graphene layers twisted against each other. The system thus virtually generates its own internal magnetic field, creating a diode effect.

Promising material graphene

The diode effect described in Nature Physics was produced with graphene, a material consisting of a single layer of carbon atoms arranged in a honeycomb pattern. Stacking several layers of graphene leads to completely new properties, including the ability of three graphene layers twisted against each other to conduct electric current without loss. The fact that a superconducting diode effect exists without an external magnetic field in this system has great implications for the study of the complex physical behavior of twisted trilayer graphene, as it demonstrates the coexistence of superconductivity and magnetism. This shows that the diode effect not only has technological relevance, but also has the potential to improve our understanding of fundamental processes in many-body physics. The theoretical basis for this has already been published in another high-ranking publication.


Story Source:

Materials provided by University of Innsbruck. Note: Content may be edited for style and length.


Journal References:

  1. Jiang-Xiazi Lin, Phum Siriviboon, Harley D. Scammell, Song Liu, Daniel Rhodes, K. Watanabe, T. Taniguchi, James Hone, Mathias S. Scheurer, J.I.A. Li. Zero-field superconducting diode effect in small-twist-angle trilayer graphene. Nature Physics, 2022; DOI: 10.1038/s41567-022-01700-1
  2. Harley D Scammell, J I A Li, Mathias S Scheurer. Theory of zero-field superconducting diode effect in twisted trilayer graphene. 2D Materials, 2022; 9 (2): 025027 DOI: 10.1088/2053-1583/ac5b16

Cite This Page:

University of Innsbruck. "Super­con­duct­ing diode with­out mag­netic field in mul­ti­layer graphene." ScienceDaily. ScienceDaily, 17 August 2022. <www.sciencedaily.com/releases/2022/08/220817104033.htm>.
University of Innsbruck. (2022, August 17). Super­con­duct­ing diode with­out mag­netic field in mul­ti­layer graphene. ScienceDaily. Retrieved October 13, 2024 from www.sciencedaily.com/releases/2022/08/220817104033.htm
University of Innsbruck. "Super­con­duct­ing diode with­out mag­netic field in mul­ti­layer graphene." ScienceDaily. www.sciencedaily.com/releases/2022/08/220817104033.htm (accessed October 13, 2024).

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