Correspondence between microwave and submillimeter absorptivity in epitaxial thin films of YBa2Cu3O7

D. Miller, P. L. Richards, S. Etemad, A. Inam, T. Venkatesan, B. Dutta, X. D. Wu, C. B. Eom, T. H. Geballe, N. Newman, B. F. Cole

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Abstract

We have measured the low-temperature loss in six epitaxial ab-plane films of the high-Tc superconductor YBa2Cu3O7 over a factor of 2000 in frequency. Submillimeter measurements from 25 to 700 cm-1 were made at 2 K by a direct absorption technique in which the film acts as the absorbing element in a composite bolometric detector. Microwave measurements near 10 GHz (0.3 cm-1) were made on five of the same films by resonance techniques at 4 K. The ∼0.4-μm-thick films were grown epitaxially on SrTiO3, LaAlO3, and MgO by off-axis sputtering and laser deposition. The absorptivities measured for all films studied are qualitatively similar, increasing smoothly with frequency, with no gaplike features below the well-known absorption edge at 450 cm-1. A successful three-parameter fit is obtained for all of our films. This 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 λg 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-Kronig analysis of the absorptivity data.

Original languageEnglish (US)
Pages (from-to)8076-8088
Number of pages13
JournalPhysical Review B
Volume47
Issue number13
DOIs
StatePublished - Jan 1 1993

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ASJC Scopus subject areas

  • Condensed Matter Physics

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Miller, D., Richards, P. L., Etemad, S., Inam, A., Venkatesan, T., Dutta, B., Wu, X. D., Eom, C. B., Geballe, T. H., Newman, N., & Cole, B. F. (1993). Correspondence between microwave and submillimeter absorptivity in epitaxial thin films of YBa2Cu3O7. Physical Review B, 47(13), 8076-8088. https://doi.org/10.1103/PhysRevB.47.8076