Third-order local nonlinear microwave response of YBa sub(2)Cu sub(3)O sub(7) and Nb thin films

• Published in: IEEE transactions on applied superconductivity Vol. 11; no. 1 I; pp. 131 - 134
• Main Authors: Pestov, E E, Nozdrin, Y N, Kurin, V V
• Format: Journal Article
• Language: English
• Published: 01.03.2001
• ISSN: 1051-8223

HTS thin films continue to be of interest for passive device applications at microwave frequencies, but nonlinear effects may limit their performance. We report a set of experimental data on local third-harmonic generation at microwave frequencies (0.5 GHz) in YBa sub(2)Cu sub(3)O sub(7) and Nb thin films from 4.2 K to T sub(c). For local investigations of the nonlinear response a probe with inductive coupling was developed. The map of the nonlinear microwave response of YBa sub(2)Cu sub(3)O sub(7) thin film is plotted below T sub(c) with high resolution. The third-harmonic power is measured as a function of temperature, input power and dc magnetic field on some places of the film. The temperature dependence demonstrates a peak of nonlinearity below T sub(c) for YBa sub(2)Cu sub(3)O sub(7) and Nb films and a minimum of nonlinearity at low temperatures for HTS films. The behavior of the third-harmonic power vs the input power can be described by the power-law with the exponent n[similar to]1.5-3. The correlation between the depinning current density J sub(p) and the nonlinear microwave response is also demonstrated.