Direct submillimeter absorptivity measurements on epitaxial Ba1-xKxBiO3 films at 2K

D. Miller, P. L. Richards, E. J. Nicol, E. S. Hellman, E. H. Hartford, C. E. Platt, R. A. Schweinfurth, D. J. VanHarlingen, J. Amano

Research output: Contribution to journalArticlepeer-review


We have used a bolometric technique to obtain accurate low temperature loss data for epitaxial thin films of Ba0.6K0.4BiO3 from 30 cm-1 to 700 cm-1. These films were grown on MgO and SrTiO3 substrates by MBE, off-axis sputtering and laser deposition techniques. All films show a strong absorption onset near the BCS tunneling gap of 3.5kBTc. We have analyzed these data using a Kramers-Kronig transformation and have corrected for finite film thickness effects. Our results indicate that the absorption onset is consistent with a superconducting energy gap. Comparison is made with predictions based on strong coupling Eliashberg theory using α2F(ω) spectra obtained from the literature. While we are able to fit the overall measured absorptivity, we are unable to fit the structure observed in our data.

Original languageEnglish (US)
Pages (from-to)1323-1326
Number of pages4
JournalJournal of Physics and Chemistry of Solids
Issue number10
StatePublished - Oct 1993


  • BKBO
  • high temperature superconductivity
  • infrared spectroscopy
  • thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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