Kondo effect and superconductivity in niobium with iron impurities

Abstract 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...

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Autores principales:	Hansong Zeng, Dan Zhou, Guoqing Liang, Rujun Tang, Zhi H. Hang, Zhiwei Hu, Zixi Pei, X. S. Ling
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/2aaa5453a93942b380bd385fcf679e88
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spelling	oai:doaj.org-article:2aaa5453a93942b380bd385fcf679e882021-12-02T16:24:50ZKondo effect and superconductivity in niobium with iron impurities10.1038/s41598-021-93731-62045-2322https://doaj.org/article/2aaa5453a93942b380bd385fcf679e882021-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-93731-6https://doaj.org/toc/2045-2322Abstract 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 $$^{\circ }$$ ∘ 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 $$\sim $$ ∼ 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.Hansong ZengDan ZhouGuoqing LiangRujun TangZhi H. HangZhiwei HuZixi PeiX. S. LingNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Hansong Zeng Dan Zhou Guoqing Liang Rujun Tang Zhi H. Hang Zhiwei Hu Zixi Pei X. S. Ling Kondo effect and superconductivity in niobium with iron impurities
description	Abstract 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 $$^{\circ }$$ ∘ 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 $$\sim $$ ∼ 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.
format	article
author	Hansong Zeng Dan Zhou Guoqing Liang Rujun Tang Zhi H. Hang Zhiwei Hu Zixi Pei X. S. Ling
author_facet	Hansong Zeng Dan Zhou Guoqing Liang Rujun Tang Zhi H. Hang Zhiwei Hu Zixi Pei X. S. Ling
author_sort	Hansong Zeng
title	Kondo effect and superconductivity in niobium with iron impurities
title_short	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_sort	kondo effect and superconductivity in niobium with iron impurities
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/2aaa5453a93942b380bd385fcf679e88
work_keys_str_mv	AT hansongzeng kondoeffectandsuperconductivityinniobiumwithironimpurities AT danzhou kondoeffectandsuperconductivityinniobiumwithironimpurities AT guoqingliang kondoeffectandsuperconductivityinniobiumwithironimpurities AT rujuntang kondoeffectandsuperconductivityinniobiumwithironimpurities AT zhihhang kondoeffectandsuperconductivityinniobiumwithironimpurities AT zhiweihu kondoeffectandsuperconductivityinniobiumwithironimpurities AT zixipei kondoeffectandsuperconductivityinniobiumwithironimpurities AT xsling kondoeffectandsuperconductivityinniobiumwithironimpurities
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Kondo effect and superconductivity in niobium with iron impurities

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