Strong damping of the c-axis plasmon in high-Tc cuprate superconductors

✍ Scribed by Jae H. Kim; H.S. Somal; M.T. Czyzyk; D. van der Marel; A. Wittlin; A.M. Gerrits; V.H.M. Duijn; N.T. Hien; A.A. Menovsky

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 877 KB
• Volume: 247
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(95)00198-0

✦ Synopsis

We analyze the infrared reflectivity of Lal.85Sr0.~sCuO4 single crystals with E parallel to the c-axis. The plasma edge at around 6 meV (50 cm -I ), which occurs only for T < T¢, is due to Cooper-pair tunneling. This low value of the plasma edge is shown to be consistent with the c-axis plasma frequency obtained from LDA band structure calculations (> 0.1 eV) if we take into account that the single-particle charge transport along the c-axis is strongly incoherent in the normal state, and remains so in the superconducting state. From a comparison of the optical conductivity with model calculations based on sand d-wave weak-coupling theory in the dirty limit, we find no evidence for a reduction of the c-axis quasi-particle scattering rate below T~. The c-axis scattering rate, the normal-state c-axis plasma frequency, and Tc obey hT > hvp >> 3.5kBTc, which is exactly opposite to the clean limit.