For 20 years, the physics of high-temperature superconductivity has been studied, but remains unsolved. Most authors believe that the superconductivity resides in the suprate planes which are common to all such superconductors, involves Cooper pairs that are of d-like symmetry, and can involve either n-type or p-type superconductivity. We shall present evidence that all three of these concepts are invalid.
There are materials which superconduct at high temperatures, despite having negligible numbers of suprate planes, most notably doped Ba2YRuO6 with onset Tc of 93K, and its sister compounds doped Sr2YRuO6 (onset Tc of 49K). The other sister compounds, undoped GdSr2Cu2RuO8 and Gd2-zCezSr2Cu2RuO10, whose suprate planes are either weakly ferromagnetic or antiferromagnetic (and presumably not superconducting), superconduct in their BaO or SrO layers.
In the most studied superconductor, YBa2Cu3O7, muon spectroscopy shows that there are two contributions to the superconductivity: (i) the temperature-activated fluxon depinning which should be corrected for first, and (ii) the basic superconductivity which has no significant Cu component, and therefore must reside in the BaO layers, no in the CuO2 or CuO planes. This superconductivity has s-wave (rather than d-wave) symmetry, and is p-type in all high-temperature superconductors. (when Pb2Sr2CaCu3O8 is dopes n-type with Am+4 or Ce+4 replacing Ca+2, it does not superconduct at all.)
Many data show that high-Tc superconductivity occurs in the BaO or similar layers, involves a normal n-type layer (such as that in the suprate-planes), and a p-type layer, such as BaO or SrO.