Investigation Details of Vortex Density in Laser-Written Π-Shaped Channel of YBCO Bridge by Means of I-V Dependences

Abstract

A current-self-induced magnetic field Hj, such that Hc1 < Hj < Hc2 at T < Tc, penetrates a thin-film, type-II superconductor forming the Abrikosov magnetic vortex-antivortex pairs in the film's areas of weakest superconductivity. Our atomic force microscopy and scanning tunneling microscopy images confirm that in 50 µm wide, 100 µm long and 0.3 µm thick YBa2Cu3O7−x superconducting devices magnetic flux penetrates first into a 5 µm wide, Π-shaped and partially deoxygenated (x ≈ 0.2) channel for easy vortex motion. When the Lorentz force overcomes pinning force in the channel, the flux starts to move and its drift dissipates energy inducing dc voltage. This work reports on the density of coherently moving vortices along the channel vs. temperature in range from 0.93Tc to 0.97Tc. Our simulations show that the vortex density vs. temperature dependence extracted from I-V measurements of our devices follows the temperature dependence of magnetic field penetration depth and the coherence length of the superconductor.

Coherent Vortex Motion in Yba2cu3o7-Z Superconducting Thin Films Containing Π-Shaped Channel for Easy Vortex Motion Biased at I ~ Ic / Magnetinių Sūkurių Koherentinio Judėjimo Yba2cu3o7-X Superlaidžiuosiuose Plonuosiuose Sluoksniuose Su Lazeriu Suformuotu

“…Todėl, superlaidininku tekant srovei, sūkurių kanalo srityje pirmiausia ir atsiranda Abrikosovo magnetiniai sūkuriai, o srovei viršijus I c vertę, sūkuriai joje pradeda judėti. Sūkurių judėjimas pasireiškia energijos nuostoliais voltamperinėse charakteristikose, atspindėtais elektrinės įtampos, proporcingos sūkurių skaičiui ir jų tankiui (Steponavičienė et al 2009(Steponavičienė et al , 2011.…”

Investigation of Optically Modified YBa2Cu3O7–x Films by Means of X-ray Microanalysis Technique

“…The stepped-like I-V dependence is a hallmark of the coherent motion of Abrikosov vortices moving along oxygen partially supressed line (i. e., in a strictly confined geometry). Such a superconducting constriction can be used as a sensitive device [10] for measuring the strength of either the current or amplitude of the external magnetic field with a precision of a single flux quantum. However, the processes causing the oxygen out-diffusion from the orthorhombic YBCO material and the profile change of the laser-deoxygenated line due to the oxygen redistribution is still not clearly understood.…”