High-transition-temperature superconductivity arises in copper oxides when holes or electrons are doped into the CuO2 planes of their insulating parent compounds. While hole-doping quickly induces metallic behavior and superconductivity in many cuprates, electron-doping alone is insufficient in materials such as R2CuO4 (R is Nd, Pr, La, Ce, etc.), 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.
@article{arxiv.cond-mat/0701345,
title = {Microscopic annealing process and its impact on superconductivity in T'-structure electron-doped copper oxides},
author = {Hye Jung Kang and Pengcheng Dai and Branton J. Campbell and Peter J. Chupas and Stephan Rosenkranz and Peter L. Lee and Qingzhen Huang and Shiliang Li and Seiki Komiya and Yoichi Ando},
journal= {arXiv preprint arXiv:cond-mat/0701345},
year = {2007}
}
Comments
23 pages, 3 figures, accepted for publication in Nature Materials