Alkaline-earth layer high-temperature superconductivity

• Published in: Physica. C, Superconductivity Superconductivity, 2007-09, Vol.460-462 (1), p.499-500
• Main Authors: Dow, John D., Harshman, Dale R.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Effects of material synthesis, crystal structure, and chemical composition; Exact sciences and technology; High-Tc compounds; Physics; Superconductivity; Transition temperature variations; Y-based cuprates
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2007.03.081

Many experiments show that cuprate-planes are not needed for high-Tc superconductivity. For example, doped Ba2YRuO6 and Sr2YRuO6 superconduct at Tc∼93K and ∼49K, have no cuprate-planes, and superconduct in their BaO and SrO planes. GdSr2Cu2RuO8 and Gd2−zCezSr2Cu2RuO10 superconduct in their SrO layers, despite having non-superconducting cuprate-planes. Muon spectroscopy of YBa2Cu3O7 shows that its BaO layers superconduct, and its cuprate-planes do not. The superconductivity of YBa2Cu3O7 is s-wave, not d-wave, once flux-pinning is corrected for. Photoemission and scanning tunneling microscopy measurements correctly show the importance of the cuprate-planes, but do not show their superconductivity. Superconductivity is detected by muon spectroscopy of YBa2Cu3O7 and occupies the BaO layers, and not the cuprate-planes. Our work contradicts the cuprate-plane models of high-temperature superconductivity, and is fully consistent with specific heat and thermal conductivity measurements, which cuprate-plane models are not.