Abstract
We have improved a microwave self-resonant technique to measure surface resistance Rs directly and surface inductance Ls indirectly. For films prepared by the laser ablation technique we observed that Rs 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 X 10-4 Ω. We measured the London penetration depth λ and coherence length ξ, and found that both λand ξ are anisotropic. Their values depended on the direction of the microwave electric field relative to the c axis. We deduced the value of λ∥ (0) to be about 1800 Å, λ∥ (86.5) about 8000 Å, and λ⊥(86.5) about 26000 Å, where λ∥ (0) is the penetration depth (as T --> 0 K) for the electromagnetic electric field parallel and λ⊥ perpendicular to the film plane. In addition ξ∥ was determined to be 129 Å and ξ⊥ equal to 40 Å at 86.5 K. The anisotropic factor γ is about 3.
Keywords
microwave self-resonant technique, surface resistance, London penetration depth, coherence length, YBaCuO films, microwave frequencies, surface inductance, MSR, EPR
Subject Categories
Electron paramagnetic resonance
Disciplines
Electrical and Computer Engineering
Publisher
American Physical Society
Publication Date
4-1-1994
Rights Information
Copyright 1994 American Physical Society
Rights Holder
American Physical Society
Permanent URL
Recommended Citation
Jiang, H.; Yuan, T.; How, H.; Widom, A.; Vittoria, C.; Chrisey, D.; Horwitz, J.; and Drehman, A., "Measurements of surface impedance, London penetration depth, and coherence length in YBaCuO films at microwave-frequencies" (1994). Electrical and Computer Engineering Faculty Publications. Paper 83. http://hdl.handle.net/2047/d20002254
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Notes
Originally published in Physical Review B 49, 9924-9932 (1994). doi 10.1103/PhysRevB49.9924 (http://link.aps.org/doi/10.1103/PhysRevB49.9924).