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- Title
Study of the Nonlinear Response of Superconductors in the Microwave Band Using a Local Technique.
- Authors
Aladyshkin, A. Yu.; Andronov, A. A.; Pestov, E. E.; Nozdrin, Yu. N.; Kurin, V. V.; Cucolo, A. M.; Monaco, R.; Boffa, M.
- Abstract
Using a local technique, we study the microwave radiation power P3ω(T,Pω,Hdc) at the triple frequency of the main signal as a function of the temperature T, the input power Pω, and the external magnetic field Hdc perpendicular to the superconductor surface for YBa2Cu3O7 (YBCO) films, monocrystals, and polycrystals and for Nb films. The most distinctive feature of the temperature dependence P3ω(T) of nonlinear response of superconductors is a maximum of the nonlinearity near the critical temperature Tc. Spatial distributions of the third-harmonic power are obtained for YBCO films at various temperatures. These distributions are indicative of a nonuniform distribution of Tc over the superconductor surface. Additional nonlinearity maxima are discovered in the dependence P3ω(T) for YBCO films and monocrystals at temperatures about 2Tc/3. These maxima are probably related to the existence of several superconducting phases with different critical temperatures. For Nb films, the second nonlinearity maximum in the dependence P3ω(T) appears only in the presence of an external magnetic field. The experimental data are interpreted within the framework of a two-fluid model of a superconductor, which takes into account the phenomenological nonlinear relationship between the vector potential A and the supercurrent js(A). The origin of nonlinearity in the studied superconductors is discussed.
- Subjects
SUPERCONDUCTORS; MICROWAVES; RADIATION; TEMPERATURE; CRYSTALS
- Publication
Radiophysics & Quantum Electronics, 2003, Vol 46, Issue 2, p109
- ISSN
0033-8443
- Publication type
Article
- DOI
10.1023/A:1023949506091