New technique for measuring the microwave penetration depth in high-Tc superconducting thin films

The ferromagnetic resonance (FMR) technique has been used to obtain the microwave (MW) penetration depth in high-temperature superconductor (HTSC) thin film. An FMR-signal-generating thin permalloy film was sandwiched in between of two YBa2Cu3O7 films to probe the MW field penetrating through the films. Below the superconducting transition temperature Tc. the HTSC films started to screen the marker inside the sandwich. The low-temperature saturation value λab ≃ 1250 Å at 25 K has been deduced for our c-axis films from the temperature dependence of the FMR signal intensity below Tc. © 2000 Elsevier Science B.V. All rights reserved