Metal-insulator transition in the Gd-doped (R1-yGdy)1.85Ce0.15CuO 4-δ systems occurred around y ∼ 0.1 for R = Eu and y ∼ 0.65 for R = Nd with a simultaneous structural transition from the tetragonal T′-phase (space group I4/mmm) to an orthorhombic O′-phase (Acam, a0 ≤ b0 ∼ √2at). The structural distortion is due to the lattice mismatch between smaller (R,Gd,Ce)2O2 layer and CuO2 plane which results in an oxygen distortion in the otherwise perfect CuO2 square plane. The phase diagram indicates that the superconductivity can only occur in the metallic T′-phase cuprates where the metallic state is controlled by a delicate balance between oxygen reduction and structural stability. The Cu2+ weak-ferromagnetic/canted-antiferromagnetic (WF/CAF) order observed in the insulating region is the direct result of non-180° α(Cu-O-Cu) canting angle of the O′-phase.
|頁（從 - 到）||922-923|
|期刊||Physica B: Condensed Matter|
|出版狀態||已發佈 - 2000|
|事件||Yamada Conference LI - The International Conference on Strongly Correlated Electron Systems (SCES '99) - Nagano, 日本|
持續時間: 1999 八月 24 → 1999 八月 28
ASJC Scopus subject areas