Anomalous microwave response of high-temperature superconducting thin-film microstrip resonator in weak dc magnetic fields

作者：Rao XS^*; Ong CK; Jin BB; Tan CY; Xu SY; Chen P; Li J; Feng YP

来源：Physica C-Superconductivity and Its Applications, 1999, 328(1-2): 60-66.

DOI：10.1016/S0921-4534(99)00534-1

• surface impedance
• high-temperature superconducting thin film
• non-linearity

We have studied an anomalous microwave (mw) response of superconducting YBa2Cu3O7-delta (YBCO) microstrip resonators in the presence of a weak dc magnetic field, H-dc. The surface resistance (R-s) and reactance (X-s) show a correlated non-monotonic behavior as a function of H-dc. R-s and X-s were found to initially decrease with elevated H-dc and then increase after H-dc reaches a crossover field, H-c, which is independent of the amplitude and frequency of the input mw signal within the measurements. The frequency dependence of R-s is almost linear at fixed H-dc with different magnitudes (< H-c, = H-c and > H-c). The impedance plane analysis demonstrates that r(H), which is defined as the ratio of the change in R-s(H-dc) and that in X-s(H-dc), is about 0.6 at H-dc < H-c and 0.1 at H-dc > H-c. The H-dc dependence of the surface impedance is qualitatively independent of the orientation of H-dc.

• 出版日期1999-12-1