Anomalies in Nonlinear Microwave Surface Impedance of YBCO Thin Films on MgO:  Superconductor Versus Substrate Effects

AV Velichko; David Huish; Michael Lancaster; A Porch

doi:10.1109/TASC.2003.812407

Anomalies in Nonlinear Microwave Surface Impedance of YBCO Thin Films on MgO: Superconductor Versus Substrate Effects

AV Velichko, David Huish, Michael Lancaster, A Porch

Electronic, Electrical and Systems Engineering

Research output: Contribution to journal › Article

5 Citations (Scopus)

Abstract

The nonlinear microwave surface impedances Z(s) = R-s + jX(s) of three epitaxial YBa2Cu3O7-delta (YBCO) thin films deposited by thermal co-evaporation on MgO substrates have been, studied by the coplanar resonator technique at 8 GHz in the temperature T range 12 to 60-K in both zero and finite (similar to10 mT) DC magnetic fields. All the films exhibited an anomalous decrease in the. sur face resistance. R. as a function of microwave magnetic field H-rf below 20 K. In one of the films, the application of a DC. field of 10 mT has also induced an anomalous decrease in the penetration depth lambda (H-rf). Analysis of the results suggests that the anomalies may be originating both in the film and in the substrate, and ways to distinguish between the two contributions are proposed. The consequences of the observed phenomena for application of YBCO films in microwave devices are discussed.

Original language	English
Pages (from-to)	3598-3601
Number of pages	4
Journal	IEEE Transactions on Applied Superconductivity
Volume	13
Issue number	2
DOIs	https://doi.org/10.1109/TASC.2003.812407
Publication status	Published - 1 Jun 2003

Keywords

microwave nonlinearity
DC magnetic field
anomalous response
high temperature superconductor

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title = "Anomalies in Nonlinear Microwave Surface Impedance of YBCO Thin Films on MgO: Superconductor Versus Substrate Effects",

abstract = "The nonlinear microwave surface impedances Z(s) = R-s + jX(s) of three epitaxial YBa2Cu3O7-delta (YBCO) thin films deposited by thermal co-evaporation on MgO substrates have been, studied by the coplanar resonator technique at 8 GHz in the temperature T range 12 to 60-K in both zero and finite (similar to10 mT) DC magnetic fields. All the films exhibited an anomalous decrease in the. sur face resistance. R. as a function of microwave magnetic field H-rf below 20 K. In one of the films, the application of a DC. field of 10 mT has also induced an anomalous decrease in the penetration depth lambda (H-rf). Analysis of the results suggests that the anomalies may be originating both in the film and in the substrate, and ways to distinguish between the two contributions are proposed. The consequences of the observed phenomena for application of YBCO films in microwave devices are discussed.",

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AU - Huish, David

AU - Lancaster, Michael

AU - Porch, A

PY - 2003/6/1

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N2 - The nonlinear microwave surface impedances Z(s) = R-s + jX(s) of three epitaxial YBa2Cu3O7-delta (YBCO) thin films deposited by thermal co-evaporation on MgO substrates have been, studied by the coplanar resonator technique at 8 GHz in the temperature T range 12 to 60-K in both zero and finite (similar to10 mT) DC magnetic fields. All the films exhibited an anomalous decrease in the. sur face resistance. R. as a function of microwave magnetic field H-rf below 20 K. In one of the films, the application of a DC. field of 10 mT has also induced an anomalous decrease in the penetration depth lambda (H-rf). Analysis of the results suggests that the anomalies may be originating both in the film and in the substrate, and ways to distinguish between the two contributions are proposed. The consequences of the observed phenomena for application of YBCO films in microwave devices are discussed.

AB - The nonlinear microwave surface impedances Z(s) = R-s + jX(s) of three epitaxial YBa2Cu3O7-delta (YBCO) thin films deposited by thermal co-evaporation on MgO substrates have been, studied by the coplanar resonator technique at 8 GHz in the temperature T range 12 to 60-K in both zero and finite (similar to10 mT) DC magnetic fields. All the films exhibited an anomalous decrease in the. sur face resistance. R. as a function of microwave magnetic field H-rf below 20 K. In one of the films, the application of a DC. field of 10 mT has also induced an anomalous decrease in the penetration depth lambda (H-rf). Analysis of the results suggests that the anomalies may be originating both in the film and in the substrate, and ways to distinguish between the two contributions are proposed. The consequences of the observed phenomena for application of YBCO films in microwave devices are discussed.

KW - microwave nonlinearity

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Anomalies in Nonlinear Microwave Surface Impedance of YBCO Thin Films on MgO: Superconductor Versus Substrate Effects

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Keywords

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