Far-infrared reflectivity of a Tl0.55Pb0.45Sr2CaCu2O7 ceramic in the normal and superconducting state

✍ Scribed by T. Zetterer; W. Ose; M. Franz; H.H. Otto; K.F. Renk

• Book ID: 103941707
• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 142 KB
• Volume: 162-164
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(89)90600-x

✦ Synopsis

We report on a study of the far-infrared reflectivity of a highly reflecting, sintered (TIo.55Pbo.45)Sr2CaCu207 sample with Tc ~-70 K. In the superconducting state the reflectivity is almost equal to 1 up to 110 cm-~; for higher frequencies the reflectivity decreases and crosses, at 400 cm -1, the reflectivity curve of the normalconducting state (at 80 K). The reflectivity in the superconducting state remains then smaller than in the normalconducting state up to 600 cm -1. The far-infrared reflectivity of our ceramic sample shows a strong similarity with that of ceramic YBa2Cus07, however, the phonon structure is more pronounced.

The phonon structure is becoming sharper with decreasing temperature and phonon frequencies increase.

We find evidence for a superconducting energy gap with a minimum value 2A/kBTc .~ 2.3 (for T << To) and an indication for a second gap (at 400 cm -~) with 2A/kBTc ..~ 8.