Variation of crystal symmetry, superconductivity and weak ferromagnetism in (R1-yGdy)1.85Ce0.15CuO 4-δ (R = Nd, Eu) cuprates

B. N. Lin, H. C. Chiang, Y. H. Lin, H. B. Yang, Y. Y. Hsu, H. M. Luo, H. C. Ku

Research output: Contribution to journalConference article

Abstract

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.

Original languageEnglish
Pages (from-to)922-923
Number of pages2
JournalPhysica B: Condensed Matter
Volume281-282
DOIs
Publication statusPublished - 2000 Jan 1
EventYamada Conference LI - The International Conference on Strongly Correlated Electron Systems (SCES '99) - Nagano, Japan
Duration: 1999 Aug 241999 Aug 28

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Keywords

  • Distorted T′-phase (O′-phase)
  • Superconductivity
  • Weak ferromagnetism

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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