Physicotechnological Principles of Deposition of Thin High-Tc Superconducting Films of YBa2Cu3O7−δ

Abstract

The careful experimental and theoretical studies followed by a subsequent improvement of high-Tc superconducting YBa2Cu3O7−δ films’ and buffer CeO2 layers’ deposition technologies with a use of laser and magnetron deposition techniques are carried out in order to obtain СеО2-buffered high-Tc superconducting YBa2Cu3O7−δ films with a controllable crystalline structure and high superconducting properties. As a result of this work, the physical and technological backgrounds of the deposition processes of perfect YBa2Cu3O7−δ films on dielectric (sapphire) substrates with a use of buffer CeO2 layers are developed for both two-beam laser and magnetron deposition techniques. The optimization of technological regimes is performed for both these deposition methods. As shown, at optimal conditions, it is possible to obtain epitaxial YBCO films with a controllable nanostructure by the use of both laser and magnetron deposition techniques. This gives in turn a possibility to change in a controllable way the main electrodynamical characteristics of superconducting YBCO films such as critical-current density and microwave surface impedance. In particular, our experiments revealed that the critical-current density, Jc, of YBCO films (77 K) strongly depends on the density of linear defects (edge dislocations) and can vary within the range of 105–7⋅106 A/cm2 when the edge-dislocations’ density varies within the range of 1010–1011 cm−2. The microwave surface resistance, Rs(77 K, 135 GHz), for this range of dislocation densities varies within the interval of 115–160 mΩ, respectively. The elaborated technologies of epitaxial YBCO films’ deposition can be used for production of HTSC-film microwave filters, which are of great interest for applications in the cellular and satellite telecommunication as well as for production of conducting elements with a large current-carrying capability for electrotechnical purposes.

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