Muon spin rotation (μ+SR) measurements conducted on crystalline YBa 2 Cu 3 O 7 are consistent with s-wave pairing, not d-wave, suggesting that the superconducting hole condensate resides in the BaO layers, not in the cuprate-planes. The specific heat and thermal conductivity data are explained by the superconducting BaO layers alone, unlike the failed interpretation based on CuO 2-plane superconductivity. The layer charges of the CuO 2 planes are almost -2 | e |, indicating that those planes are primarily carriers of electrons, not holes. The cuprate-planes are not the dominant hole-carriers of high- T C superconductivity, as demonstrated by doped YBa 2 RuO 6, which has no such CuO 2 lanes, yet superconducts at ~ 93 K. Moreover the trio of related compounds, YSr 2 RuO 6 (doped with Cu on Ru sites), undoped GdSr 2 Cu 2 RuO 8, and undoped Gd 2-z Ce z Sr 2 Cu 2 RuO 10 all start superconducting near 49 K in their SrO layers, not in the cuprate planes of the two compounds that have such planes, because those planes are either antiferromagnetic or weakly ferromagnetic and so do not superconduct. In PrBa 2 Cu 3 O 7, a Pr -on- Ba -site ( Pr Ba) defect kills the superconductivity, but Pr -on- Pr -site ( Pr Pr) does not. Both defects are approximately equidistant from the intervening cuprate plane, suggesting that the cuprate plane does not carry significant superconductivity. In GdBa 2 Cu 3 O 7, Gd -on-a- Gd -site ( Gd Gd) does not break Cooper pairs, but Gd -on-a- Ba -site ( Gd Ba) does, indicating that the superconductivity is in the BaO layers, and not in the cuprate-planes. In HgBa 2 Ca n-1 Cu n O 2n+2, the BaO layers, not the cuprate-planes, gain positive charge as T C, pressure, and the number of layers n increase. The reason that theories based on holes in the cuprate-planes have done so poorly is that those planes were incorrectly identified as the source of high-temperature superconductivity on the basis of a single datum by Cava et al., that was first contradicted by Jorgensen et al., and then endorsed by Jorgensen alone on the basis of the Cava datum, not his own. This error is the main reason why cuprate-plane superconductivity, which probably does not exist, has been so widely accepted.
Cation Distributions and Magnetic Properties of Ferrispinel MgFeMnO4