Enhancement of the critical current density in CaKFe4As4 single crystals through 3 MeV proton irradiation.

W. MEIER; P. C. CANFIELD; MINGYU XU; S. BUD´KO; N. HABERKORN; S. SUAREZ

SUPERCONDUCTOR SCIENCE AND TECHNOLOGY

IOP PUBLISHING LTD

Lugar: Londres; Año: 2020 vol. 33 p. 25008 - 25015

0953-2048

We study the influence of random point disorder on the vortex dynamics and critical current densities Jc 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/cm2 to 4×1016 p/cm2. The results show the addition of extrinsic random point disorder enhances the Jc 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/cm2, increasing Jc at 5 K by factors » 5 and 14 at self-field and m0H = 3 T, respectively. We analyze the vortex dynamics using the collective creep theory. The enhancement in Jc matches with a systematic reduction in the flux creep relaxation rates as a consequence of a gradual increase in the collective pinning energy U0. The substantial increment in Jc produced by random point disorder, reaching values of 9 MA/cm2 at 5 K and self-field, makes CaKFe4As4 a promising material for applications based on current carrying capacity at high magnetic fields.