A Structural Parameter for High Tc Superconductivity from an Octahedral Moebius Strip in RBaCuO:123 type Perovskites

Abstract

An index for the characterisation of the Perovskite type Superconductors is introduced. The index, denominated as Structural Parameter of High Tc Superconductivity (PESATc from its name in Spanish), is calculated using a Moebius Orbital defined as the length of an Octahedral Moebius Strip overlaying the octahedra created by the CuO planes and the apical Oxygen atoms, O(4). Results for structures of YBCO:123 type compounds are presented; their atomic positions were measured by neutron diffraction and x-ray diffraction techniques as reported in the literature. It has been found that critical temperature depends on the value of the measured structural parameter; furthermore, for a set of RBCO compounds there is a lineal response between Tc and PESATc. In the former case, a specific range for the superconducting behaviour is established by PESATc values, and a well-defined point for the maximum Tc is found. In the latter one, a slope of 4.515 with correlation coefficient of 0.9402 was found when seven Rare Earth compounds were considered. The only compound that goes out from this trend, is the La based compound.