The reflectivity R (ω) of both the ab plane and the c axis of two single crystals of La1.875 Ba0.125-y Sry Cu O4 has been measured down to 5 cm-1, using coherent synchrotron radiation below 30 cm-1. For y=0.085, a Josephson plasma resonance is detected at T Tc =31 K in the out-of-plane Rc (ω), and a far-infrared peak (FIP) appears in the in-plane optical conductivity σab (ω) below 50 K, where nonstatic charge ordering (CO) is reported by x-ray scattering. For y=0.05 (Tc =10 K), below the ordering temperature TCO, a FIP is again observed in σab (ω). The FIP then appears to be an infrared signature of CO, either static or fluctuating, as reported in previous work on the La-Sr cuprates.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2006|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics