Deviations from plastic barriers inBi2Sr2CaCu2O8+δthin films

Abstract

Resistive transitions of an epitaxial Bi2Sr2CaCu2O 8+δ thin film were measured in various magnetic fields (H c), ranging from 0 to 22.0 T. Rounded curvatures of low resistivity tails are observed in Arrhenius plot and considered to relate to deviations from plastic barriers. In order to characterize these deviations, an empirical barrier form is developed, which is found to be in good agreement with experimental data and coincide with the plastic barrier form in a limited magnetic field range. Using the plastic barrier predictions and the empirical barrier form, we successfully explain the observed deviations.

Iron chalcogenide superconductors at high magnetic fields

“…Deviation from the Arrhenius relation indicates that the assumptions of constant ρ 0 f and linear temperature dependence of U (T, µ 0 H ) could be invalid in S-09. If U (T, µ 0 H ) = U 0 (µ 0 H )(1 − t) and ρ 0 f = const, this will result in −∂ ln ρ(T, µ 0 H )/∂ T increases sharply with decreasing temperature, which was also observed in Bi-2212 thin films [55]. The center of each U 0 (µ 0 H ) horizontal line approximately intersects the (5) and (6)).…”

“…On the other hand, the values of q change from about 1 for H c to 2 for H ab, independent on the field intensity for both directions ( figure 3(b)). The value of q = 2 has also been observed in many cuprates superconductors [55][56][57].…”

Anisotropic pinning defects in BaZrO3-doped YBa2Cu3O6+x films in high magnetic fields

“…The dependence of the resistivity on temperature and magnetic field can be described by a function qðT ; BÞ / e ÀU ðBÞ=T , where U ðBÞ ¼ U 0 =B a is the pinning potential which has a power-law dependence on B [27]. Therefore the behavior of the normalized resistivity q norm ðB; HÞ measured at a constant temperature taking into account the geometry of the measurement, is given by the equation…”

Thermally activated energy and critical magnetic fields of SmFeAsO0.9F0.1

“…Generally, the TAE of CBS is analyzed by equation (1) using an assumption that the prefactor 2ρ c U/T is temperature independent, and ln ρ(H, T ) linearly depends on 1/T with the form ln ρ(H, T ) = ln ρ 0 (H) − U 0 (H)/T , where H is the magnetic field strength, ln ρ 0 (H) = ln ρ 0f +U 0 (H)/T c [note that ln ρ 0 (H) is the ln ρ(H) value for 1/T → 0], ρ 0f the constant, U 0 the TAE for T → 0, and T c the superconducting transition temperature. The importance is that the analysis leads to U = U 0 (1 − t), and the apparent activate energy −∂ ln ρ/∂T −1 = U 0 , where t = T /T c [22,23,24,25,26,27,28,29,30,31]. By drawing resistivity data in the so-called Arrhenius plot with a relation ln ρ(H, 1/T ), one can easily determine U 0 (H) with its corresponding slope in a low resistivity range.…”

“…The vortex dynamics of CBS have been widely studied in theories and experiments [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31]. According to the theory, the thermally activated flux flow (TAFF) resistivity is expressed as ρ = (2ν 0 LB/J) exp(−J c0 BV L/T ) sinh(JBV L/T ) [18,19,20,21,22], where ν 0 is an attempt frequency for a flux bundle hopping, L the hopping distance, B the magnetic induction, J the applied current density, J c0 the critical current density in the absence of flux creep, V the bundle volume, and T the temperature.…”