Current Distribution in Y-Ba-Cu-O Superconducting Microbridges Containing Π-Shaped Channel for Easy Vortex Motion

Abstract

A mixed state in dc-biased thin films of II-type superconductors realizes the Abrikosov magnetic vortices/ antivortices, which are the result of the current-self magnetic field penetration into the film at temperatures lower than its critical temperature Tc. A nucleation of vortices/antivortices at the superconducting film's edges, their motion perpendicular to the direction of biasing current, and the annihilation in the film's center originates from a current dissipation in the superconductor and expresses itself in experiments as a dc voltage. This work reports on the results of simulation of current density in a 50 µm wide, 100 µm long, and 0.3 µm thick YBa2Cu3O7−x microbridges containing Π-shaped 5 µm wide single channel of easy vortex motion fabricated by means of laser-writing technique. Analyzing a two-dimensional-net of resistors and assuming that, due to the Meissner-Ochsenfeld effect, the magnetic flux penetration into superconducting film is nonlinear, we demonstrate that presence of a Π-shaped channel causes a non-homogeneous distribution of current in the microbridge.

Study of Energy Dissipation in the Mixed-State YBa2Cu3O7-δ Superconductor with Partially Deoxygenated Structures

“…Due to the Meissner-Ochsenfeld effect at temperatures T < Tc and the presence of the 10 μm wide partially deoxygenated structure in the YBCO device, the current density in the central part of the device is higher compared to that of sample 2, in which the partially deoxygenated structure makes a 40 μm wide rectangle. Narrowing the rectangle, the bias current focuses on a central part of the device [20] (bottleneck), resulting in a larger amplitude of the electric field there than on the sidewalks of this rectangle (i.e., between the sides of the rectangle structure and the edges of the device (Figure 1)). Due to vortex motion in partially deoxygenated regions, resistivity does not drop to zero but shows a repetitive recovery until ~50 μΩ cm in the biased sample 1 at temperatures T < 88 K (Figure 2a).…”