FAR-INFRARED TRANSMISSION STUDY ON ND1.85CE0.15CUO4-Y THIN-FILMS

Far-infrared transmission of Nd1.85Ce0.15CuO4-y thin films (T-c = 19 K ) has been measured in the frequency range of 15 similar to 150 cm(-1) . An energy-gap-like peak is observed in T-s/T-n at 40 cm(-1) (drop E( p)), corresponding to E(p) similar to 3.0kT(c), which is reminiscent o f the BCS-type superconductors. On the other hand, both the temperatur e and magnetic-field dependence of the peak show a non-BCS-like behavi or. Also, reducing T-c to 12 K by oxygen depletion does not affect the peak energy, for which E(p) = 4.8kT(c) is extracted. The similarities of these observations to the case of YBa2Cu3O7-x are discussed.