On the effect of atom substitutions and pressure on the superconductivity of yttrium cuprates

✍ Scribed by V.I. Makarov; V.Z. Kleiner; O.N. Ovcharenko; N.S. Tereshina; V.A. Finkel'; V.N. Golovin; V.V. Derevyanko

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 532 KB
• Volume: 219
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90379-4

✦ Synopsis

The effect of atom substitutions on Tc variation under pressure is investigated for YBa2Cu3_xAgxOT_6 (1-2-3), 0 < x< 0.5, and Y1 _xCaxBa2CuaOs_, (1-2-4), 0 < x< 0.3. A non-linear concentration dependence of two types is observed for the dTJdP derivative. In the 1-2-3 system this variable reaches saturation at x=0.3, whereas in the 1-2-4 phase it has its minimum at x=0.1. The non-linear dependence of dTc/dP(x) with extremum in 1-2-4 is apparently due to the electron-topology phase transition caused by doping. A weaker dependence of Tc and dTJdP in 1-2-3 under substitution for Cu atoms may be due to the influence of the processes of carrier scattering on the anisotropy of the order parameter of the superconductor. From the function T~(x) for the 1-2-3 phase we have calculated the ratio of the coherence length ?-.o to the free length l in YBa2Cu3_ ~Ag~OT_6. The temperature dependence of the contribution of superconducting fluctuations in YBa2Cu3_xAgxO7_~ is found to agree with the Aslamazov-Larkin theory.