title: Microscopic annealing process and its impact on superconductivity in T'-structure electron-doped copper oxides.
abstract: High-transition-temperature superconductivity arises in copper oxides when holes or electrons are doped into the CuO(2) 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 R(2)CuO(4) (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 CuO(2) 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.
authors.affiliation: Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA. hkang@nist.gov
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Kang
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Dai
authors.forename: Branton J
authors.initials: BJ
authors.lastname: Campbell
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Chupas
authors.forename: Stephan
authors.initials: S
authors.lastname: Rosenkranz
authors.forename: Peter L
authors.initials: PL
authors.lastname: Lee
authors.forename: Qingzhen
authors.initials: Q
authors.lastname: Huang
authors.forename: Shiliang
authors.initials: S
authors.lastname: Li
authors.forename: Seiki
authors.initials: S
authors.lastname: Komiya
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ando