Far-Infrared Optical Conductivity Gap in Superconducting [Formula presented] Films

Robert A. Kaindl, Marc A. Carnahan, Joseph Orenstein, Daniel S. Chemla, Hans M. Christen, Hong Ying Zhai, Mariappan Paranthaman, Doug H. Lowndes

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We report the first study of the optical conductivity of [Formula presented] covering the range of its lowest-energy superconducting gap. Terahertz time-domain spectroscopy is utilized to determine the complex, frequency-dependent conductivity [Formula presented] of thin films. The imaginary part reveals an inductive response due to the emergence of the superconducting condensate. The real part exhibits a strong depletion of oscillator strength near 5 meV resulting from the opening of a superconducting energy gap. The gap ratio of [Formula presented] is well below the weak-coupling value, pointing to complex behavior in this novel superconductor.

Original languageEnglish (US)
Pages (from-to)4
Number of pages1
JournalPhysical Review Letters
Issue number2
StatePublished - 2002
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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