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Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties

Heterogeneous superconductivity onset is a common phenomenon in high-T [Formula: see text] superconductors of both the cuprate and iron-based families. It is manifested by a fairly wide transition from the metallic to zero-resistance states. Usually, in these strongly anisotropic materials, supercon...

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Autores principales: Grigoriev, Pavel D., Kochev, Vladislav D., Orlov, Andrey P., Frolov, Aleksei V., Sinchenko, Alexander A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10003944/
https://www.ncbi.nlm.nih.gov/pubmed/36902961
http://dx.doi.org/10.3390/ma16051840
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author Grigoriev, Pavel D.
Kochev, Vladislav D.
Orlov, Andrey P.
Frolov, Aleksei V.
Sinchenko, Alexander A.
author_facet Grigoriev, Pavel D.
Kochev, Vladislav D.
Orlov, Andrey P.
Frolov, Aleksei V.
Sinchenko, Alexander A.
author_sort Grigoriev, Pavel D.
collection PubMed
description Heterogeneous superconductivity onset is a common phenomenon in high-T [Formula: see text] superconductors of both the cuprate and iron-based families. It is manifested by a fairly wide transition from the metallic to zero-resistance states. Usually, in these strongly anisotropic materials, superconductivity (SC) first appears as isolated domains. This leads to anisotropic excess conductivity above T [Formula: see text] , and the transport measurements provide valuable information about the SC domain structure deep within the sample. In bulk samples, this anisotropic SC onset gives an approximate average shape of SC grains, while in thin samples, it also indicates the average size of SC grains. In this work, both interlayer and intralayer resistivity were measured as a function of temperature in FeSe samples of various thicknesses. To measure the interlayer resistivity, FeSe mesa structures oriented across the layers were fabricated using FIB. As the sample thickness decreases, a significant increase in superconducting transition temperature T [Formula: see text] is observed: T [Formula: see text] raises from 8 K in bulk material to 12 K in microbridges of thickness ∼40 nm. We applied analytical and numerical calculations to analyze these and earlier data and find the aspect ratio and size of the SC domains in FeSe consistent with our resistivity and diamagnetic response measurements. We propose a simple and fairly accurate method for estimating the aspect ratio of SC domains from T [Formula: see text] anisotropy in samples of various small thicknesses. The relationship between nematic and superconducting domains in FeSe is discussed. We also generalize the analytical formulas for conductivity in heterogeneous anisotropic superconductors to the case of elongated SC domains of two perpendicular orientations with equal volume fractions, corresponding to the nematic domain structure in various Fe-based superconductors.
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spelling pubmed-100039442023-03-11 Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties Grigoriev, Pavel D. Kochev, Vladislav D. Orlov, Andrey P. Frolov, Aleksei V. Sinchenko, Alexander A. Materials (Basel) Article Heterogeneous superconductivity onset is a common phenomenon in high-T [Formula: see text] superconductors of both the cuprate and iron-based families. It is manifested by a fairly wide transition from the metallic to zero-resistance states. Usually, in these strongly anisotropic materials, superconductivity (SC) first appears as isolated domains. This leads to anisotropic excess conductivity above T [Formula: see text] , and the transport measurements provide valuable information about the SC domain structure deep within the sample. In bulk samples, this anisotropic SC onset gives an approximate average shape of SC grains, while in thin samples, it also indicates the average size of SC grains. In this work, both interlayer and intralayer resistivity were measured as a function of temperature in FeSe samples of various thicknesses. To measure the interlayer resistivity, FeSe mesa structures oriented across the layers were fabricated using FIB. As the sample thickness decreases, a significant increase in superconducting transition temperature T [Formula: see text] is observed: T [Formula: see text] raises from 8 K in bulk material to 12 K in microbridges of thickness ∼40 nm. We applied analytical and numerical calculations to analyze these and earlier data and find the aspect ratio and size of the SC domains in FeSe consistent with our resistivity and diamagnetic response measurements. We propose a simple and fairly accurate method for estimating the aspect ratio of SC domains from T [Formula: see text] anisotropy in samples of various small thicknesses. The relationship between nematic and superconducting domains in FeSe is discussed. We also generalize the analytical formulas for conductivity in heterogeneous anisotropic superconductors to the case of elongated SC domains of two perpendicular orientations with equal volume fractions, corresponding to the nematic domain structure in various Fe-based superconductors. MDPI 2023-02-23 /pmc/articles/PMC10003944/ /pubmed/36902961 http://dx.doi.org/10.3390/ma16051840 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Grigoriev, Pavel D.
Kochev, Vladislav D.
Orlov, Andrey P.
Frolov, Aleksei V.
Sinchenko, Alexander A.
Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties
title Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties
title_full Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties
title_fullStr Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties
title_full_unstemmed Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties
title_short Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties
title_sort inhomogeneous superconductivity onset in fese studied by transport properties
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10003944/
https://www.ncbi.nlm.nih.gov/pubmed/36902961
http://dx.doi.org/10.3390/ma16051840
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