Measurement of the far-infrared magnetoconductivity tensor of superconducting YBa₂Cu₃O_7-δ thin films

We report measurements of the far-infrared transmission of superconducting YBa₂Cu₃O_7-δ thin films from 5 to 200 cm^-1 in fields up to 14 T. A Kramers-Kronig analysis of the magnetotransmission spectrum yields the magnetoconductivity tensor which is found to be dominated by three terms: a London term, a low frequency Lorentzian\(ω1∼3 cm^-1\) of width γ1 = 10 cm^-1, and a finite frequency Lorentzian of width γ2 = 17 cm^-1 at ω2 = 24 cm^-1 in the hole cyclotron resonance active mode of circular polarization.