The Investigation of Vortex Motion in the YBCO Devices Manufactured Utilizing a Gaussian-shaped Optical Spot from a Continuous-wave Laser

Abstract

The current report focuses on the analysis of the investigation results of the Abrikosov vortex motion in the YBa₂Cu₃O_7-d (YBCO) device, which is a c-axis textured 0.3 ´ 50 ´ 100 µm³ (thickness ´ width ´ length) stripe of YBCO superconductor deposited on a LaAlO₃ substrate. A laser beam focused in a Gaussian-shape optical spot of 5 mm in diameter modifies the stripe, initiating the oxygen out-diffusion and its uneven distribution in illuminated areas and in this way causing the appearance of a higher level of deoxygenation in the spot center and a lower level at its edges (slopes of weak superconductivity region). At temperatures below the temperature of the superconducting transition T_c, the current-self-produced magnetic field penetrates the optically modified area of the stripe in a form of Abrikosov magnetic vortices, and due to the current-self-produced Lorentz force, the vortices move toward their annihilation line resulting in energy dissipation. The vortices pinned on the slopes experience strong pinning and exert a magnetic drag force on moving vortices, which is confirmed by the stepped current-voltage dependences of the YBCO devices measured at temperatures 0.933·T_c £ T £ 0.958·T_c. Our results demonstrate the advantages of partially deoxygenated YBCO material for the development of superconducting electronic devices with electronic properties controlled by the motion of Abrikosov vortices at temperatures below T_c of the superconductor.