Article abstract

Nature Materials 6, 224 - 229 (2007)
Published online: 18 February 2007 | doi:10.1038/nmat1847

Subject Categories: Electronic materials | Superconductors

Microscopic annealing process and its impact on superconductivity in T'-structure electron-doped copper oxides

Hye Jung Kang1,2,3, Pengcheng Dai1,4, Branton J. Campbell5, Peter J. Chupas6, Stephan Rosenkranz6, Peter L. Lee7, Qingzhen Huang2, Shiliang Li1, Seiki Komiya8 & Yoichi Ando8

High-transition-temperature superconductivity arises in copper oxides when holes or electrons are doped into the CuO2 planes of their insulating parent compounds. Whereas hole doping quickly induces metallic behaviour and superconductivity in many cuprates, electron doping alone is insufficient in materials such as R2CuO4 (R is Nd, Pr, La, Ce and so on), where it is necessary to anneal an as-grown sample in a low-oxygen environment to remove a tiny amount of oxygen in order to induce superconductivity. Here we show that the microscopic process of oxygen reduction repairs Cu deficiencies in the as-grown materials and creates oxygen vacancies in the stoichiometric CuO2 planes, effectively reducing disorder and providing itinerant carriers for superconductivity. The resolution of this long-standing materials issue suggests that the fundamental mechanism for superconductivity is the same for electron- and hole-doped copper oxides.

  1. Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA
  2. NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8562, USA
  3. Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742-2115, USA
  4. Neutron Scattering Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA
  5. Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
  6. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
  7. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
  8. Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan

Correspondence to: Hye Jung Kang1,2,3 e-mail:

Correspondence to: Pengcheng Dai1,4 e-mail:


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