Anisotropic thermally activated flux flow and flux flow in Bi2Sr2CaCu2Oy crystals

Non-ohmicI-Vbehaviour in granular and high- superconductors

“…Deviation from linearity occurs at T nl < T c . Estimation of the pinning barrier U 0 using the model of Sun et al qualitatively agrees with the activation energy values obtained by Wördenweber's model and other experimental data [3,7,19].…”

“…Moreover we have obtained U 0 = 10.03 eV using the data of Dubson et al for a polycrystalline Y(123) sample [8]. These values are in a close agreement with the simulated activation energy obtained by Wördenweber and other experimental values [7,19,3]. The small U 0 value obtained for Bi(2223) compared to Y(123) is related to the differences in the effective mass ratio , where (Bi(2223)) ≈ 100 (Y(123)) [19].…”

“…Thin films [1][2][3] and single crystals [4,3] as well as polycrystalline [5,8,6,11] and melt-textured samples [10] have been studied. Such dissipative properties are sensitive to the magnetic field applied when parallel or perpendicular to the passing current [9,10,7]. High magnetic fields (> 10 4 Oe) are often required to observe appreciable changes in the transition width (≈ 10 K) in single crystals and thin films, while it takes a few oersteds to observe similar broadening effects in granular high-T c superconductors [8,12].…”