Critical Current Density of YBa{2}Cu{3}O{7-d} Low-Angle Grain Boundaries in Self-Field

Grain boundaries (GBs) have been shown to limit critical current density, Jc, in YBa2Cu3O7 (YBCO) coated conductors. Here we use transport measurements and scanning Hall probe microscopy coupled with current reconstruction to demonstrate that GB geometry, such as the in-plane meandering observed in films grown by metalorganic deposition (MOD) on rolling assisted biaxially textured substrate (RABiTS), can lead to higher GB Jc. We observe current-induced flux entry into such a ...

We report on transport properties of grain boundaries fabricated in YBa2Cu3O7-x thin films grown by the liquid phase epitaxy (LPE) technique on MgO asymmetrical bicrystal substrate with 45o misorientation angle. In total around 10 samples have been studied. Substantial scatter of zero field values of the critical current density at 5K has been observed. The upper limit of Jc of the order of 104 A/cm2 found in our study is close to previously reported data for 45o bicrystals g...

The interface properties of high-temperature cuprate superconductors have been of interest for many years, and play an essential role in Josephson junctions, superconducting cables, and microwave electronics. In particular, the maximum critical current achievable in high-Tc wires and tapes is well known to be limited by the presence of grain boundaries, regions of mismatch between crystallites with misoriented crystalline axes. In studies of single, artificially fabricated gr...

Most measurements of critical current densities in YBa$_2$Cu$_3$O$_{7-\delta}$ thin films to date have been performed on films where the \textit{c}-axis is grown normal to the film surface. With such films, the analysis of the dependence of $j_c$ on the magnetic field angle is complex. The effects of extrinsic contributions to the angular field dependence of $j_c$, such as the measurement geometry and disposition of pinning centres, are convoluted with those intrinsically due...

A rapid decrease in the critical current density (Jc) of YBa2Cu3O7-x (YBCO) films with increasing film thickness has been observed for multiple YBCO growth processes. While such behavior is predicted from 2D collective pinning models under certain assumptions, empirical observations of the thickness dependence of Jc are believed to be largely processing dependent at present. To investigate this behavior in ex situ YBCO films, 2.0 and 2.9 um thick YBCO films on ion beam assist...

In this investigation we report the determination of the critical current density $J_c$ flowing in a $\mathrm{Y}\mathrm{Ba}_2\mathrm{Cu}_3\mathrm{O}_{7-\delta}$ superconducting thin film. Estimation of $J_c$ was carried out by an inductive technique, the so-called screening technique, in which both the imaginary part of the fundamental harmonic of susceptibility $\chi''_1$ and third harmonic voltage $V_3$ criteria were considered for the determination of the full penetration ...

Doping is one of the most relevant paths to tune the functionality of cuprates, it determines carrier density and the overall physical properties of these impressive superconducting materials. We present an oxygen doping study of YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) thin films from underdoped to overdoped state, correlating the measured charge carrier density, $n_\textrm{H}$, the hole doping, $p$, and the critical current density, $J_\textrm{c}$. Our results show a continuous i...

There are numerous potential applications for superconducting tapes, based on YBa2Cu3O7-x (YBCO) films coated onto metallic substrates. A long established goal of more than 15 years has been to understand the magnetic flux pinning mechanisms which allow films to maintain high current densities out to high magnetic fields. In fact, films carry 1-2 orders of magnitude higher current densities than any other form of the material. For this reason, the idea of further improving pi...

Critical current density Jc in polycrystalline or granular superconducting material is known to be hysteretic with applied field H due to the focusing of field within the boundary between adjacent grains. This is of concern in the so-called coated conductors wherein superconducting film is grown on a granular, but textured surface of a metal substrate. While previous work has mainly been on Jc determined using induced or magnetization currents, the present work utilizes trans...

Flux pinning scaling laws were developed to explain the observed increase in the critical current density Jc caused by increased density of grain boundaries in polycrystalline low temperature superconductors (LTS) such as Nb3Sn. For four decades they have provided the framework for the successful development of the LTS materials that carry high Jc in high magnetic fields. However, the discovery of the weak-link problem suggested that transmission of supercurrent flow through ...