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Proceedings Paper

Residual loss lin high-Tc superconductors from microwave to infrared frequencies
Author(s): P. L. Richards
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Paper Abstract

We have measured the low temperature loss in epitaxial films of high-Tc oxide superconductors over a' factor 3000 in frequency. Submillirneter measurements from 25 to 700 cm-1 were made at 21( by a novel direct absorption technique in which the film acts as the absorbing element in a composite bolometric detector. Microwave measurements near 10 GMz (0.3 cwt) were made on many of the same elms by resonance techniques at 4K. The absorptivities measured for YBaCuO (123) films are qualitatively similar, increasing smoothly with frequency, with no gap-like features below the well known absorption edge at 450 cm-1. A successful three parameter fit can be interpreted either in terms of a weakly coupled grain model or a homogeneous two-fluid model with residual normal conductivity. The fitting parameters correspond to a grain penetration depth A.g equal to the muon spin relaxation value of 140 nm, and to reasonable grain properties. They also give carrier densities in reasonable agreement with optically determined plasma frequencies and conductivities in agreement with a Kramers-Krortig analysis of the absorptivity data. Qualitatively similar behavior was observed in films of TiCaBaCuO (222310 and 212.28). Films of BKBO, by contrast, show a BCS-like energy gap.

Paper Details

Date Published: 1 January 1994
PDF: 1 pages
Proc. SPIE 2250, International Conference on Millimeter and Submillimeter Waves and Applications 1994, 22503T (1 January 1994); doi: 10.1117/12.2303154
Show Author Affiliations
P. L. Richards, Univ. of California, Berkeley (United States)

Published in SPIE Proceedings Vol. 2250:
International Conference on Millimeter and Submillimeter Waves and Applications 1994
Mohammed N. Afsar, Editor(s)

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