Far-infrared sphere resonance in Bi2Sr2CaCu2O8+δ samples with various oxygen concentrations is measured down to 5 cm-1. Although no peaks are observed in this frequency range for the optimumly doped sample, the Josephson plasma peak is observed at 5 cm-1 for a 1-atm-O2-annealed sample. The peak shifts to higher frequencies as the doping increases, and is observed at 11 cm-1 for a 150-atm-O2-annealed sample. The c-axis penetration depth λc obtained from the peak frequencies is determined to be 77 to 35 μm. These large λc values are larger than the value estimated from the Josephson-coupled layer model, while the doping dependence is qualitatively explained by the model.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 1999 May 1|
ASJC Scopus subject areas
- Condensed Matter Physics