For Gd2CuO4, a symmetry-forbidden phonon for the tetragonal T' structure is observed. This shows that oxygen in the CuO2 plane is locally distorted along the plane. Such distortion has not been observed for other T'-type superconductors. The normal-mode calculation shows that the correlation between the CuO2 plane and R-O layers increases with decreasing ionic radius. The increased three-dimensional character and the appearance of the distortion of O in the CuO2 plane along the a axis are useful experimental results that help clarify the mechanism that causes the disappearance of superconductivity for Gd.
ASJC Scopus subject areas
- Condensed Matter Physics