Herstellung und Charakterisierung epitaktischer Hochtemperatur-Supraleiter-Schichten
Herstellung und Charakterisierung epitaktischer Hochtemperatur-Supraleiter-Schichten
Two types of high temperature superconductor films have been prepared by diode sputtering in a high oxygen atmosphere and subsequent in situ annealing in oxygen. Both, the YBa2Cu307_o and Bi2Sr2CaCu20S+o-films, showed an excellent c-axis orientation, as veriefied by X-ray diffraction and Rutherford...
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Personal Name(s): | Osthöver, Claudius (Corresponding author) |
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Contributing Institute: |
Institut für Festkörperforschung; IFF |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
1994
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Physical Description: |
75 S. |
Document Type: |
Report |
Series Title: |
Berichte des Forschungszentrums Jülich
2953 |
Subject (ZB): | |
Link: |
OpenAccess |
Publikationsportal JuSER |
Two types of high temperature superconductor films have been prepared by diode sputtering in a high oxygen atmosphere and subsequent in situ annealing in oxygen. Both, the YBa2Cu307_o and Bi2Sr2CaCu20S+o-films, showed an excellent c-axis orientation, as veriefied by X-ray diffraction and Rutherford backscattering spectrum measurements. The rocking curve of YBa2Cu307_o showed a full width at half maximum value (FWHM) of 0.17°, and. Bi2Sr2CaCu20s+o showed 0.15°. The minimum yield ofthe channeling measurements is lower then 2 % for YBa2Cu307-8, and 9 % for Bi2Sr2CaCu20S+o' The minimum yield for the Bi-superconductor is higher because of its incommensurable structure in the BiO-plane. The magnetic properties of the films were measured with a SQUID-magnetometer. Both kinds of films have the same critical temperature of approximatly 91 Kelvin. However, the zero-field-cooled suscebilities for both cases were quite different: for fields of about B =0.1 mT the transisiton curve is broaden for Bi2Sr2CaCu20S+o in contrast to the the curves of the YBa2Cu307_o-filmS. Critical current estimations done with a SQUID-magnetomer yielded for YBa2Cu307_o-films at 5 K JcC5K)= 6.0 107 A/cm2, and at 77 Kelvin JcC77K) = 3.7 106 A/cm2, for Bi2Sr2CaCu20S+o at 5 K JcC5K) = 1.0 107 A/cm2, at 77 K JcC77K) = 1.0 104 A/cm2. The different behaviour of both samples in an external magnetic field can be explained by a strong different anisotropy ofthe superconducting properties. At fixed temperature the form of the magnetization curves for both kinds of superconducting films with c-axis parallel to the extern field (N ~ 1) can be described with a modell calculation by Mikheenko et al. [1]. The curvature ofthe magnetic field lines and not the gradient of the fluxlines parallel to the field as in the simple Beanmodel determines the critical current. Additionally the flux-penetration was observed using the magneto-optical Faraday-effect. These observations support the results of the magnetization measurements |