Current distribution in YBa₂Cu₃O_7-x superconducting thin film micro-bridges containing laser–written -shaped channel for easy vortex motion have been investigated in a narrow range of temperatures ranging from 85.7 to 90.2 K, which are below the critical temperature T_c of the material. In the range of the before mentioned temperatures the current-self magnetic field produced, Abrikosov magnetic vortices/anti-vortices appear in the partially deoxygenated (x ~ 0.2) channel and move coherently identifying itself as Josephson–like voltage “steps” in nonlinear current–voltage dependences. Bias current creates Lorentz force F_L, pushing vortices along the LW-channel from its edges towards the centre. As follows from current-voltage dependences, vortices start moving at I = I_c. This current already satisfies condition F_L >> F_p (where F_p – is pinning force in the film). Our results confirm that coherent vortex motion in the channel holds even at high biasing current when I ~ 200I_c. However, at these biasing currents, the width of voltage steps appears to be shorter than at lower current. This phenomenon has been explained by means of the onset of additional vortex motion in the laser untreated regions of the superconducting device. These regions are located in between the Π-shaped channel for easy vortex motion. Our results also demonstrate the possibility of investigating the electric properties of the mixed state superconductor by means of current dissipation due to the onset of coherent vortex motion.

Article in Lithuanian