Ames Laboratory; Physics and Astronomy
Ames Laboratory, Physics and Astronomy
Superconductor Science and Technology
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)
Department of Energy Subject Categories
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Iowa State University Digital Repository, Ames IA (United States)