Enhancement of critical current density in CaKFe4As4 single crystals through 3 MeV proton irradiation. (7th January 2020)

• Record Type: Journal Article
• Authors: Haberkorn, N; Xu, M; Meier, W R; Suárez, S; Bud'ko, S L; Canfield, P C
• Is Part Of: Superconductor science & technology. Volume 33:Number 2(2020:Feb.)
• Publication Date: 2020-01-07
• Subjects: iron based superconductors -- critical current densities -- irradiation; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/ab5f4b
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: We study the influence of random point disorder on the vortex dynamics and critical current densities J c of CaKFe4 As4 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 × 10 15 p cm −2 to 4 × 10 16 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 × 10 16 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 CaKFe4 As4 a promising material for applications based on current carrying capacity at high magnetic fields.