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

The ferromagnetic resonance (FMR) technique has been used to obtain the mic rowave (MW) penetration depth in high-temperature superconductor (HTSC) thi n film. An FMR-signal-generating thin permalloy film was sandwiched in betw een of two YBa2Cu3O7 films to probe the MW field penetrating through the fi lms. Below the superconducting transition temperature T-c the HTSC films st arted to screen the marker inside the sandwich. The low-temperature saturat ion value lambda(ab) similar or equal to 1250 Angstrom at 25 K has been ded uced for our c-axis films from the temperature dependence of the FMR signal intensity below T-c. (C) 2000 Elsevier Science B.V. All rights reserved.