High-temperature Superconductivity: Status

A theory of high-temperature superconductivity is presented which (i) explains the cuprates, with cuprate-planes; (ii) describes the superconducting ruthenates without cuprate-planes, such as Ba$_2$YRuO$_6$; (iii) treats the rutheno-cuprates, such as GdSr$_2$Cu$_2$RuO$_8$, whose cuprate-planes do not superconduct; (iv) treats the molecule $\kappa$-[BEDT-TTF]$_2$Cu [NCS]$_2$ which superconducts via S, and (v)explains the pnictides. In YBa$_2$Cu$_3$O$_7$, the theory is consistent with the observation that no Cu-containing plane superconducts and the observed superconductivity is $s$-wave, not $d$-wave, once fluxon-de-pinning has been properly accounted for. The superconducting layers are BaO layers, are $p$-type, and are adjacent to the $n$-type cuprate-planes. The theory is consistent with many data which were previously beyond explanation.