Suppression of vortex channeling in meandered YBa2Cu3O7-d grain boundaries

We report on the in-plane magnetic field (H) dependence of the critical current density (Jc) in meandered and planar single grain boundaries (GBs) isolated in YBa2Cu3O7-d (YBCO) coated conductors. The Jc(H)properties of the planar GB are consistent with those previously seen in single GBs of YBCO films grown on SrTiO3 bi-crystals. In the straight boundary a characteristic flux channeling regime when H is oriented near the GB plane, associated with a reduced Jc, is seen. The meandered GB does not show vortex channeling since it is not possible for a sufficient length of vortex line to lie within it.Comment: Submitted to AP

Vortex deformation and breaking in superconductors: A microscopic description

Vortex breaking has been traditionally studied for nonuniform critical current densities, although it may also appear due to nonuniform pinning force distributions. In this article we study the case of a high-pinning/low-pinning/high-pinning layered structure. We have developed an elastic model for describing the deformation of a vortex in these systems in the presence of a uniform transport current density $J$ for any arbitrary orientation of the transport current and the magnetic field. If $J$ is above a certain critical value, $J_c$, the vortex breaks and a finite effective resistance appears. Our model can be applied to some experimental configurations where vortex breaking naturally exists. This is the case for YBa$_2$Cu$_3$O$_{7-x}$ (YBCO) low angle grain boundaries and films on vicinal substrates, where the breaking is experienced by Abrikosov-Josephson vortices (AJV) and Josephson string vortices (SV), respectively. With our model, we have experimentally extracted some intrinsic parameters of the AJV and SV, such as the line tension $\epsilon_l$ and compared it to existing predictions based on the vortex structure.Comment: 11 figures in 13 files; minor changes after printing proof

The critical current of YBa2Cu3O7-d Low Angle Grain Boundaries

Transport critical current measurements have been performed on 5 degree [001]-tilt thin film YBa2Cu3O7-delta single grain boundaries with magnetic field rotated in the plane of the film, phi. The variation of the critical current has been determined as a function of the angle between the magnetic field and the grain boundary plane. In applied fields above 1 T the critical current, j_c, is found to be strongly suppressed only when the magnetic field is within an angle phi_k of the grain boundary. Outside this angular range the behavior of the artificial grain boundary is dominated by the critical current of the grains. We show that the phi dependence of j_c in the suppressed region is well described by a flux cutting model.Comment: To be published in PRL, new version with minor changes following referees report

How Differing Soil Microbial Communities and Dehydration Stress Effect Arabidopsis thaliana Morphological Development

Arabidopsis thaliana was exposed to five different soil treatments: Vermicompost, ‘Food Waste’ Compost, Potting soil (4:1 Promix BX/Perlite), Autoclaved Vermicompost and Autoclaved ‘Food Waste’ compost. Soil treatments A and B were tested for the presence of bacteria using MacConkey and Phenylethyl Alcohol media. All plants were watered on Tuesdays and Fridays and no longer received water after one month. Leaf number, stem height and length of the largest leaf were measured before and after dehydration stress. Once the dehydration stress began, the majority of the plants did not survive with the exception of the vermicompost