Defect independence of the irreversibility line in proton-irradiated Y-Ba-Cu-O crystals

Abstract

Flux pinning in Y-Ba-Cu-O crystals is studied as a function of fluence of 3-MeV protons, which create random local defects. Order-of-magnitude increases in the critical current density are deduced from magnetic hysteresis loops, with values up to 2x 10 5 A/cm 2 observed at 77 K and 1 T. However, the irreversibility line in the field-temperature plane and the pinning potentials deduced from flux-creep studies are hardly changed. These results are compared to melting and pinning models.

Nonconventional short-time dc magnetometer for superconducting films

“…The relaxation rate is in accordance with the usually reported value of 0.03 for single-crystal and ceramic YBCO samples. 1,14 With respect to t 0 , the results are in agreement with the extrapolated values in temperature from Ref. 15.…”

Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

“…These fluctuations enable vortex depinning via different types of excitations, thus effectively reducing J c . 49 In Figure 5d, we find that S is significantly reduced with respect to that of (Y,Gd)BCO when NPs are included. The stronger the pinning, the smaller S is; however, more importantly, the reduction of S(H) continues up to higher field strengths with an increasing density of BMO NPs; the maximum field for the low creep onset (μ 0 H(S onset )) is 1.5 T for the +12BZO (d coat = 150 nm) film and 3.5 T for the +12BHO (d coat = 30 nm) film (see arrows in Figure 5b).…”

“…Several models have been proposed to explain J c (T, H, θ) in cuprate and pnictide superconductors with strong pinning NPs or NRs. 21,24,[50][51][52][53][54][55][56][57][58][59] Although the influence of creep Tuning NP size for enhanced functionality M Miura et al on J c for these superconductors has been known for a long time, 49,60 only a few attempts have been made to link the pinning improvements to J c and S. 60,61 To calculate the temperature, magnetic field and field angle dependence of J c (J c;calc: ), we use J c;calc: T; H; y ð Þ¼ J c0 T; H; y ð Þ1 À Sln t=t 0 ð Þ ð Þ , where t 0 is the effective attempt time, J c0 is the creep-free J c and S is the experimentally obtained flux creep rate.…”

Fracture behavior of an inclined crack interacting with a circular inclusion in a high-TC superconductor under an electromagnetic force

“…15 It is also important that artificial microscopic defects or inclusions in superconductors are effective in increasing critical current densities. Introduction of defects by irradiation in YBa 2 Cu 3 O 7 has been proved [16][17][18][19] to result in sharp increases of critical temperatures and fields in the irreversible region. Using the top-seed-melt-textured growth process, Murakami et al 20 doped Y 2 BaCuO 5 (Y211) inclusions into the YBa 2 Cu 3 O 7−x (Y123) matrix and found that the flux-pinning force can be improved due to the dispersion of nonsuperconducting Y211 inclusions.…”