Publication Date

1-7-2020

Department

Ames Laboratory; Physics and Astronomy

Campus Units

Ames Laboratory, Physics and Astronomy

OSTI ID+

1581771

Report Number

IS-J 10109

DOI

10.1088/1361-6668/ab5f4b

Journal Title

Superconductor Science and Technology

Volume Number

33

Issue Number

2

First Page

025008

Abstract

We study the influence of random point disorder on the vortex dynamics and critical current densities J c of CaKFe4As4 single crystals by performing magnetization measurements. Different samples were irradiated with a proton (p) beam at constant energy of 3 MeV to fluencies from 2 × 1015 p cm−2 to 4 × 1016 p cm−2. The results show the addition of extrinsic random point disorder enhances the J c values at low and intermediate temperatures over the entire range of magnetic fields applied. The optimum pinning enhancement is achieved with a proton fluence of 3 × 1016 p cm−2, increasing J c at 5 K by factors ≈5 and 14 at self-field and μ 0 H = 3 T, respectively. We analyze the vortex dynamics using the collective creep theory. The enhancement in J c matches with a systematic reduction in the flux creep relaxation rates as a consequence of a gradual increase in the collective pinning energy U 0. The substantial increment in J c produced by random point disorder, reaching values of 9 MA cm−2 at 5 K and self-field, makes CaKFe4As4 a promising material for applications based on current carrying capacity at high magnetic fields.

DOE Contract Number(s)

AC02-07CH11358

Language

en

Department of Energy Subject Categories

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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