Fluctuation spectroscopy in granular superconductors with application to boron-doped nanocrystalline diamond

Perkins, D. T. S., Klemencic, G. M. ORCID: https://orcid.org/0000-0002-2125-9754, Fellows, J. M. and Smith, R. A. 2021. Fluctuation spectroscopy in granular superconductors with application to boron-doped nanocrystalline diamond. Physical Review B 104 (9) , 094513. 10.1103/PhysRevB.104.094513

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Abstract

We perform a detailed calculation of the various contributions to the fluctuation conductivity of a granular metal close to its superconducting transition. We find three distinct regions of power law behavior in reduced temperature, η = ( T − T c ) / T c , with crossovers at Γ / T c and E Th / T c , where Γ is the electron tunneling rate, and E Th is the Thouless energy of a grain. The calculation includes both intergrain and intragrain degrees of freedom. This complete theory of the fluctuation region in granular superconductors is then compared to experimental results from boron-doped nanocrystalline diamond, using the assumption of a constant phase breaking rate τ − 1 ϕ . We find a semiquantitative agreement between the theoretical and experimental results only in the case of large phase breaking. We argue that there may be a phase breaking mechanism in granular metals worthy of further experimental and theoretical investigation.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Physical Society
ISSN:	2469-9950
Date of First Compliant Deposit:	26 November 2021
Date of Acceptance:	4 August 2021
Last Modified:	11 Nov 2023 11:53
URI:	https://orca.cardiff.ac.uk/id/eprint/145758

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