Abstract
We have measured the grazing-incidence p-polarized far-infrared reflectivity of Sm2-xCexCuO4-delta crystals (T-c = 15 K). C-axis longitudinal-optical phonon features are clearly visible at 430, 570, and 600 cm(-1). The phonon frequencies do not shift with temperature, which indicates that the electronic component of the dielectric function remains almost unaltered above the energy scale of 3-4k(B)T(c) across the superconducting transition. Below T-c the absorptivity (measured down to 30 cm(-1)) does not show a signature of a threshold at around 3.5k(B)T(c) characteristic of BCS superconductivity. Based on our observations with (E) over right arrow parallel to (c) over right arrow an upper limit of 30 cm(-1) can be placed on the energy of the screened Josephson plasmon for temperatures down to 4 K.
| Original language | English |
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| Pages (from-to) | 1023-1024 |
| Number of pages | 2 |
| Journal | Physica C: Superconductivity and its Applications |
| Volume | 282 |
| Publication status | Published - Aug-1997 |
| Event | International Conference on Materials and Mechanisms of Superconductivity - High Temperature Superconductors V - Duration: 28-Feb-1997 → 4-Mar-1997 |