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The effective increase in atomic scale disorder by doping and superconductivity in Ca3Rh4Sn13

Slebarski, Andrzej, Zajdel, Pawe?, Fija?kowski, Marcin, Maska, Maciej M, Witas, Piotr, Goraus, Jerzy, Fang, Yuankan, Arnold, Donna C., Maple, M Brian (2018) The effective increase in atomic scale disorder by doping and superconductivity in Ca3Rh4Sn13. New Journal of Physics, 20 . ISSN 1367-2630. E-ISSN 1367-2630. (doi:10.1088/1367-2630/aae4a8)

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Abstract

A comprehensive study of the electronic structure, thermodynamic and electrical transport properties reveals the existence of inhomogeneous superconductivity due to structural disorder in Ca3Rh4Sn13 doped with La (Ca3−x La x Rh4Sn13) or Ce (Ca3−x Ce x Rh4Sn13) with superconducting critical temperatures T*c higher than those (T c ) observed in the parent compounds. The T − x diagrams and the entropy S(x) T isotherms document well the relation between the degree of atomic disorder and separation of the high-temperature T*c and T c -bulk phases. In these dirty superconductors, with the mean free path much smaller than the coherence length, the Werthamer–Helfand–Hohenber theoretical model does not fit well the H c2(T) data. We demonstrate that this discrepancy can result from the presence of strong inhomogeneity or from two-band superconductivity in these systems. Both the approaches very well describe the H − T dependencies, but the present results as well as our previous studies give stronger arguments for the scenario based on the presence of nanoscopic inhomogeneity of the superconducting state. A comparative study of La-doped and Ce-doped Ca3Rh4Sn13 showed that in the disordered Ca3−x Ce x Rh4Sn13 alloys the presence of spin-glass effects is the cause of the additional increase of T*c in respect to the critical temperatures of disordered Ca3−x La x Rh4Sn13. We also revisited the nature of structural phase transition at T*~130÷170 K and documented that there might be another precursor transition at higher temperatures. Raman spectroscopy and thermodynamic properties suggest that this structural transition may be associated with a CDW-type instability.

Item Type: Article
DOI/Identification number: 10.1088/1367-2630/aae4a8
Subjects: Q Science > QC Physics
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Michael Woods
Date Deposited: 03 Oct 2018 09:06 UTC
Last Modified: 12 Jul 2019 11:28 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/69347 (The current URI for this page, for reference purposes)
Arnold, Donna C.: https://orcid.org/0000-0003-0239-5790
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