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.
ASJC Scopus subject areas
- Physics and Astronomy(all)