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Preparation and characterization of high-entropy alloy (TaNb)1−x(ZrHfTi)x superconducting films


Zhang, Xiaofu; Winter, Natascha; Witteveen, Catherine; Moehl, Thomas; Xiao, Yuan; Krogh, Fabio; Schilling, Andreas; von Rohr, Fabian O (2020). Preparation and characterization of high-entropy alloy (TaNb)1−x(ZrHfTi)x superconducting films. Physical Review Research, 2(1):013375.

Abstract

We report on the preparation and the physical properties of superconducting (TaNb)1−x(ZrHfTi)x high-entropy alloy films. The films were prepared by means of magnetron sputtering at room temperature, with x ranging from 0 to 1 with an average thickness of 600–950 nm. All films crystallize in a pseudo body-centered cubic (BCC) structure. For samples with x<0.65, the normal-state properties are metallic, while for x≥0.65 the films are weakly insulating. The transition from metallic to weakly insulating occurs right at the near-equimolar stoichiometry. We find all films, except for x=0 or 1, to become superconducting at low temperatures, and we interpret their superconducting properties within the Bardeen-Cooper-Schrieffer (BCS) framework. The highest transition temperature Tc=6.9K of the solid solution is observed for x∼0.43. The highest upper-critical field Bc2(0)=11.05 T is found for the near-equimolar ratio x∼0.65, where the mixing entropy is the largest. The superconducting parameters derived for all the films from transport measurements are found to be close to those that are reported for amorphous superconductors. Our results indicate that these films of high-entropy alloys are promising candidates for superconducting device fabrication.

Abstract

We report on the preparation and the physical properties of superconducting (TaNb)1−x(ZrHfTi)x high-entropy alloy films. The films were prepared by means of magnetron sputtering at room temperature, with x ranging from 0 to 1 with an average thickness of 600–950 nm. All films crystallize in a pseudo body-centered cubic (BCC) structure. For samples with x<0.65, the normal-state properties are metallic, while for x≥0.65 the films are weakly insulating. The transition from metallic to weakly insulating occurs right at the near-equimolar stoichiometry. We find all films, except for x=0 or 1, to become superconducting at low temperatures, and we interpret their superconducting properties within the Bardeen-Cooper-Schrieffer (BCS) framework. The highest transition temperature Tc=6.9K of the solid solution is observed for x∼0.43. The highest upper-critical field Bc2(0)=11.05 T is found for the near-equimolar ratio x∼0.65, where the mixing entropy is the largest. The superconducting parameters derived for all the films from transport measurements are found to be close to those that are reported for amorphous superconductors. Our results indicate that these films of high-entropy alloys are promising candidates for superconducting device fabrication.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:30 March 2020
Deposited On:04 Jan 2021 13:50
Last Modified:19 Feb 2021 14:15
Publisher:American Physical Society
ISSN:2643-1564
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1103/physrevresearch.2.013375
Project Information:
  • : FunderSNSF
  • : Grant IDPZ00P2_174015
  • : Project TitleChemistry and Physics of Nitride Based Materials

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