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Kondo effect and superconductivity in niobium with iron impurities

Kondo effect is an interesting phenomenon in quantum many-body physics. Niobium (Nb) is a conventional superconductor important for many superconducting device applications. It was long thought that the Kondo effect cannot be observed in Nb because the magnetic moment of a magnetic impurity, e.g. ir...

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Autores principales: Zeng, Hansong, Zhou, Dan, Liang, Guoqing, Tang, Rujun, Hang, Zhi H., Hu, Zhiwei, Pei, Zixi, Ling, X. S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270948/
https://www.ncbi.nlm.nih.gov/pubmed/34244574
http://dx.doi.org/10.1038/s41598-021-93731-6
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author Zeng, Hansong
Zhou, Dan
Liang, Guoqing
Tang, Rujun
Hang, Zhi H.
Hu, Zhiwei
Pei, Zixi
Ling, X. S.
author_facet Zeng, Hansong
Zhou, Dan
Liang, Guoqing
Tang, Rujun
Hang, Zhi H.
Hu, Zhiwei
Pei, Zixi
Ling, X. S.
author_sort Zeng, Hansong
collection PubMed
description Kondo effect is an interesting phenomenon in quantum many-body physics. Niobium (Nb) is a conventional superconductor important for many superconducting device applications. It was long thought that the Kondo effect cannot be observed in Nb because the magnetic moment of a magnetic impurity, e.g. iron (Fe), would have been quenched in Nb. Here we report an observation of the Kondo effect in a Nb thin film structure. We found that by co-annealing Nb films with Fe in Argon gas at above 400 [Formula: see text] C for an hour, one can induce a Kondo effect in Nb. The Kondo effect is more pronounced at higher annealing temperature. The temperature dependence of the resistance suggests existence of remnant superconductivity at low temperatures even though the system never becomes superconducting. We find that the Hamann theory for the Kondo resistivity gives a satisfactory fitting to the result. The Hamann analysis gives a Kondo temperature for this Nb–Fe system at [Formula: see text] 16 K, well above the superconducting transition onset temperature 9 K of the starting Nb film, suggesting that the screening of the impurity spins is effective to allow Cooper pairs to form at low temperatures. We suggest that the mechanism by which the Fe impurities retain partially their magnetic moment is that they are located at the grain boundaries, not fully dissolved into the bcc lattice of Nb.
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spelling pubmed-82709482021-07-12 Kondo effect and superconductivity in niobium with iron impurities Zeng, Hansong Zhou, Dan Liang, Guoqing Tang, Rujun Hang, Zhi H. Hu, Zhiwei Pei, Zixi Ling, X. S. Sci Rep Article Kondo effect is an interesting phenomenon in quantum many-body physics. Niobium (Nb) is a conventional superconductor important for many superconducting device applications. It was long thought that the Kondo effect cannot be observed in Nb because the magnetic moment of a magnetic impurity, e.g. iron (Fe), would have been quenched in Nb. Here we report an observation of the Kondo effect in a Nb thin film structure. We found that by co-annealing Nb films with Fe in Argon gas at above 400 [Formula: see text] C for an hour, one can induce a Kondo effect in Nb. The Kondo effect is more pronounced at higher annealing temperature. The temperature dependence of the resistance suggests existence of remnant superconductivity at low temperatures even though the system never becomes superconducting. We find that the Hamann theory for the Kondo resistivity gives a satisfactory fitting to the result. The Hamann analysis gives a Kondo temperature for this Nb–Fe system at [Formula: see text] 16 K, well above the superconducting transition onset temperature 9 K of the starting Nb film, suggesting that the screening of the impurity spins is effective to allow Cooper pairs to form at low temperatures. We suggest that the mechanism by which the Fe impurities retain partially their magnetic moment is that they are located at the grain boundaries, not fully dissolved into the bcc lattice of Nb. Nature Publishing Group UK 2021-07-09 /pmc/articles/PMC8270948/ /pubmed/34244574 http://dx.doi.org/10.1038/s41598-021-93731-6 Text en © The Author(s) 2021 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Zeng, Hansong
Zhou, Dan
Liang, Guoqing
Tang, Rujun
Hang, Zhi H.
Hu, Zhiwei
Pei, Zixi
Ling, X. S.
Kondo effect and superconductivity in niobium with iron impurities
title Kondo effect and superconductivity in niobium with iron impurities
title_full Kondo effect and superconductivity in niobium with iron impurities
title_fullStr Kondo effect and superconductivity in niobium with iron impurities
title_full_unstemmed Kondo effect and superconductivity in niobium with iron impurities
title_short Kondo effect and superconductivity in niobium with iron impurities
title_sort kondo effect and superconductivity in niobium with iron impurities
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8270948/
https://www.ncbi.nlm.nih.gov/pubmed/34244574
http://dx.doi.org/10.1038/s41598-021-93731-6
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