We measured the far infrared reflectivity of two superconducting Pr 2-xCexCuCO4 films above and below T c. The reflectivity in the superconducting state increases and the optical conductivity drops at low energies, in agreement with the opening of a (possibly) anisotropic superconducting gap. The maximum energy of the gap scales roughly with Tc as 2Δmax/kBT c≈4.7. We determined absolute values of the penetration depth at 5 K as λab=(3300±700) Å for x=0.15 and λab=(2000±300) Å for x=0.17. A spectral weight analysis shows that the Ferrell-Glover-Tinkham sum rule is satisfied at conventional low energy scales -4Δmax.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Oct 2004|