The 0.3-mm-thick, 50-mm-wide and 100-mm-long YBa2Cu3O7-x superconducting bridges with a laser-written, single, Π-shaped channel have been investigated by means of electronic transport measurements at temperatures below the onset of the bridge's superconducting transition temperature. Our results demonstrate that the coherent vortex motion confined in the P-shaped channel can be used for determination of both the density and velocity of Abrikosov magnetic vortices in the channel. The coherent motion of Abrikosov vortices expresses itself as Josephson-like voltage steps, observed on the current-voltage characteristics of our microbridges, measured at zero external magnetic field, in a limited range of temperatures and bias currents. The steps' amplitude corresponds to the entrance of an additional vortex-antivortex pair into the channel's area and change in the vortex velocity. This amplitude also affects the increase of the Lorentz force for energy dissipative drift of the magnetic flux in the channel, but it does not increase, however, with the increase of the biasing current. We present and discuss the results of experimentally measured and calculated energy dissipation, which originated from variations in the vortex density and velocity when the vortices are moving along the channel of the superconducting bridge.http://dx.doi.org/10.5755/j01.ms.17.2.489
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.
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.
Santrauka.Darbe nagrinėjami silpnai tarpusavyje sąveikaujančių Abrikosovo magnetinių sūkurių judėjimo ypatumai 0,3 mm storio, 100 mm ilgio ir 50 mm pločio YBa 2 Cu 3 O 7-x superlaidžiuosiuose dariniuose, turinčiuose iš dalies deguonimi nuskurdintą Π formos Abrikosovo magnetinių sūkurių kanalą. Sūkurių kanalas superlaidžiajame darinyje sudarytas sufokusuotu į 5 mm skersmens dėmę lazerio spinduliu. Šviesos poveikiu modifikuotame superlaidžiojo darinio kanale (x < 0,2) atsirado papildomi sūkurių prieraišos centrai (deguonies vakansijos), kurių kuriama sūkurių prieraišos jėga F p sumažino stiprių prieraišos centrų kuriamą prieraišos jėgą ir sukūrė palankias sąlygas Abrikosovo magnetinių sūkurių judėjimui, dariniu tekant srovei, kurios tankis keliomis eilėmis mažesnis už šviesa nemodifikuoto superlaidininko dalies kritinį srovės tankį. Atliktų tyrimų rezultatai rodo, kad koherentinis Abrikosovo magnetinių sūkurių judėjimas superlaidininke, eksperimentuose pasireiškiantis įtampos laipteliais voltamperinėje darinio charakteristikoje, gali atsirasti esant F L >> F p netgi tuomet, kai sūkurių kanalas nėra visiškai užpildytas Abrikosovo magnetiniais sūkuriais, dėl ko sūkuriai silpnai sąveikauja tarpusavyje.Reikšminiai žodžiai: II rūšies superlaidininkas, kritinis magnetinis laukas, sūkurių prieraišos jėga, sūkurių prieraišos centrai, Lorenco jėga, Abrikosovo magnetinis sūkurys, sūkurių kanalas.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.