Far infrared optical absorption study and characterization of Y₁Ba₂Cu₃Oδ/ Pr_0.5Y_0.5Ba₂Cu₃O_7-δ superlattices

We report infrared reflection measurements on Y₁Ba₂Cu₃O_7-δ/Pr _0.5Y_0.5Ba₂Cu₃O_7-δ (60Å/60Å, 16 layers and 60Å/24Å, 16 layers on SrTiO₃ (100) substrate) high T_c superconducting superlattice films. We measured absorption spectrum of these films from 30 - 700 cm^-1(3.7 - 66.9 meV) and 80 - 300 K. These films showed resistive superconducting transitions with an on set at 80 K. Some of the phonons are smear out because of strong electron-phonon mediation. The appearance of vibration modes are around 547, 361, 279, 172, 150, 125 cm^-1 at 80 K. Some contribution and interaction between layers were observed from measured spectra. The different configuration of interlayer thickness of these superlattices have 1-2 cm^-1 peaks shift in spectra. The dielectric and electron-phonon behaviors due to interaction of superlattice layers will go further studies.