Abstract
We have improved a microwave self-resonant technique to measure surface resistance directly and surface inductance indirectly. For films prepared by the laser ablation technique we observed that at 21 GHz decreased by about three orders of magnitude as the temperature decreased from 90 to 80 K reaching a low value of 4.9× Ω. We measured the London penetration depth λ and coherence length ξ, and found that both λ and ξ are anisotropic. Their values depended on the direction of the microwave electric field relative to the c axis. We deduced the value of (0) to be about 1800 Å, (86.5) about 8000 Å, and (86.5) about 26 000 Å, where (0) is the penetration depth (as T→0 K) for the electromagnetic electric field parallel and perpendicular to the film plane. In addition was determined to be 129 Å and equal to 40 Å at 86.5 K. The anisotropic factor γ is about 3.
- Received 12 November 1993
DOI:https://doi.org/10.1103/PhysRevB.49.9924
©1994 American Physical Society