Measurements of anisotropic characteristic lengths in YBCO films at microwave-frequencies

• Online Access: http://hdl.handle.net/2047/d20002253

We used microwave self-resonant and magnetically modulated microwave absorption techniques to measure the London penetration depth, λ, and coherence length, ξ, in the direction parallel and perpendicular to the a-b plane of YBCO films. We found that both λ and ξ were anisotropic; it appeared that the value of λ∥ (0) was about 1800 Å and λ⊥(86.5) about 26 000 Å, where λ∥ is the penetration depth for the applied microwave electric field parallel and λ⊥ perpendicular to the film plane (c-axis is perpendicular to the film plane). We deduced ξ∥ to be equal to 129 Å and ξ⊥ 40 Å at 86.5 K. The anisotropy factor γ we determined to be about 3.