Structure determination of copper-oxygen planes in high temperture oxide superconductor materials by neutron scattering have shown that the Cu-O-Cu bond angles strongly deviate from 180°. This is explainable by the Cu-O bond having a strong covalent character that allows the valence-alternating pair behaviour of copper neighbours. In this case a pair of electrons — the lone pair of oxygen — oscillates between the copper ions. This mechanism allows lone pairs to mediate supercurrent like Cooper pairs. An interesting consequence of this valence alternating pair behaviour is quasi-ferroelectricity, which has an important contribution to the conducting mechanism of the supercurrent.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering