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 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

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Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS ATOMIC ORIGIN OF THE COEXISTENCE OF HIGH CRITICAL CURRENT DENSITY AND HIGH _T_C IN CUBA2CA3CU4O10+Δ SUPERCONDUCTORS Article

Open access 10 June 2022 CRITICAL ROLE OF HYDROGEN FOR SUPERCONDUCTIVITY IN NICKELATES Article 01 March 2023 SCALING OF THE STRANGE-METAL SCATTERING IN UNCONVENTIONAL SUPERCONDUCTORS Article

16 February 2022 REFERENCES * Bednorz, J. G. & Müller, K. A. Possible High _T_ c Superconductivity in the Ba–La–Cu–O System. _Z. Phys. B_ 64, 189–193 (1986). Article  CAS  Google

Scholar  * Tokura, Y., Takagi, H. & Uchida, S. A superconducting copper oxide compound with electrons as the charge carriers. _Nature_ 337, 345–347 (1989). Article  CAS  Google Scholar 

* Takagi, H., Uchida, S. & Tokura, Y. Superconductivity produced by electron doping in CuO2-layered compounds. _Phys. Rev. Lett._ 62, 1197–1200 (1989). Article  CAS  Google Scholar  *

Takayama-Muromachi, E., Izumi, F., Uchida, Y., Kato, K. & Asano, H. Oxygen deficiency in the electron-doped superconductor Nd2−_x_ Ce _x_ CuO4−_y_ . _Physica C_ 159, 634–638 (1989).

Article  CAS  Google Scholar  * Cava, R. J. et al. Metal atom stoichiometry in the electron doped superconductor (Nd,Ce)2CuO4 . _Physica C_ 199, 65–72 (1992). Article  CAS  Google Scholar  *

Kim, J. S. & Gaskell, D. R. The phase stability diagrams for the systems Nd2CuO4−_δ_ and Nd1.85Ce0.15O4−_δ_ . _Physica C_ 209, 381–388 (1993). Article  CAS  Google Scholar  * Jiang, W.,

Peng, J. L., Li, Z. Y. & Greene, R. L. Transport properties of Nd1.85Ce0.15O4+_δ_ crystals before and after reduction. _Phys. Rev. B_ 47, 8151–8155 (1993). Article  CAS  Google Scholar

  * Radaelli, P. G., Jorgensen, J. D., Schultz, A. J., Peng, J. L. & Greene, R. L. Evidence of apical oxygen in Nd2CuO _y_ determined by single-crystal neutron diffraction. _Phys. Rev.

B_ 49, 15322–15326 (1994). Article  CAS  Google Scholar  * Prado, F., Caneiro, A. & Serquis, A. Oxygen non-stoichiometry of Nd1.85Ce0.15Cu1+_δ_ O _y_ as a function of _δ_ and its

relation with the superconducting properties. _J. Therm. Anal._ 48, 1027–1038 (1997). Article  CAS  Google Scholar  * Xu, X. Q., Mao, S. N., Jiang, W., Peng, J. L. & Greene, R. L. Oxygen

dependence of the transport properties of Nd1.78Ce0.22CuO4±_δ_ . _Phys. Rev. B_ 53, 871–875 (1996). Article  CAS  Google Scholar  * Schultz, A. J., Jorgensen, J. D., Peng, J. L. &

Greene, R. L. Single-crystal neutron-diffraction structures of reduced and oxygenated Nd2−_x_ Ce _x_ CuO _y_ . _Phys. Rev. B_ 53, 5157–5159 (1996). Article  CAS  Google Scholar  * Seffar, A.

et al. Copper deficiency and superconductivity in Nd2−_x_ Ce _x_ CuO4 oxides. _Physica C_ 259, 75–82 (1996). Article  CAS  Google Scholar  * Prado, F., Briático, J., Caneiro, A., Tovar, M.

& Causa, M. T. Copper Content and Superconductivity of Nd1.85Ce0.15Cu1+_δ_ O _y_ . _Solid State Commun._ 90, 695–699 (1994). Article  CAS  Google Scholar  * Uefuji, T., Kurahashi, K.,

Fujita, M., Matsuda, M. & Yamada, K. Electron-doping effect on magnetic order and superconductivity in Nd2−_x_ Ce _x_ CuO4 single crystals. _Physica C_ 378-381, 273–277 (2002). Article 

CAS  Google Scholar  * Kurahashi, K., Matsushita, H., Fujita, M. & Yamada, K. Heat treatment effects on the superconductivity and crystal structure of Nd1.85Ce0.15CuO4 studied using a

single crystal. _J. Phys. Soc. Jpn._ 71, 910–915 (2002). Article  CAS  Google Scholar  * Richard, P. et al. Role of oxygen nonstoichiometry and the reduction process on the local structure

of Nd2−_x_ _C_ _e_ _x_ CuO4±_δ_ . _Phys. Rev. B_ 70, 064513 (2004). Article  Google Scholar  * Riou, G., Richard, P., Jandl, S., Poirier, M. & Fournier, P. Pr3+ crystal-field excitation

study of apical oxygen and reduction processes in Pr2−_x_ Ce _x_ CuO4±_δ_ . _Phys. Rev. B_ 69, 024511 (2004). Article  Google Scholar  * Matsuura, M. et al. Effect of a magnetic field on the

long-range magnetic order in insulating Nd2CuO4 and nonsuperconducting and superconducting Nd1.85Ce0.15CuO4 . _Phys. Rev. B_ 68, 144503 (2003). Article  Google Scholar  * Mang, P. K. et al.

Phase decomposition and chemical inhomogeneity in Nd2−_x_ Ce _x_ CuO4±_δ_ . _Phys. Rev. B_ 70, 094507 (2004). Article  Google Scholar  * Kang, H. J. et al. Electronically competing phases

and their magnetic field dependence in electron-doped nonsuperconducting and superconducting Pr0.88LaCe0.12CuO4±_δ_ . _Phys. Rev. B_ 71, 214512 (2005). Article  Google Scholar  * Kimura, H.

et al. X-ray and electron diffraction study of a precipitation phase in Nd1.85Ce0.15CuO4+_y_ single crystal. _J. Phys. Soc. Jpn._ 74, 2282–2286 (2005). Article  CAS  Google Scholar  *

Richard, P., Poirier, M., Jandl, S. & Fourier, P. Impact of the reduction process on the long-range antiferromagnetism in Nd1.85Ce0.15CuO4 . _Phys. Rev. B_ 72, 184514 (2005). Article 

Google Scholar  * Higgins, J. S., Dagan, Y., Barr, M. C., Weaver, B. D. & Greene, R. L. Role of oxygen in the electron-doped superconducting cuprates. _Phys. Rev. B_ 73, 104510 (2006).

Article  Google Scholar  * Tsuei, C. C. & Kirtley, J. R. Pairing symmetry in cuprate superconductors. _Rev. Mod. Phys._ 72, 969–1016 (2000). Article  CAS  Google Scholar  * Shan, L. et

al. Distinct pairing symmetries in Nd1.85Ce0.15CuO4−_y_ and La1.89Sr0.11CuO4 single crystals: evidence from comparative tunneling measurements. _Phys. Rev. B_ 72, 144506 (2005). Article 

Google Scholar  * Brese, N. E. & O’Keeffe, M. Bond-valence parameters for solids. _Acta Cryst. B_ 47, 192–197 (1991). Article  Google Scholar  * Dai, P. et al. Electronic inhomogeneity

and competing phases in electron-doped superconducting Pr0.88LaCe0.12CuO4−_δ_ . _Phys. Rev. B_ 71, 100502(R) (2005). Article  Google Scholar  * Wilson, S. D. et al. Resonance in the

electron-doped high-transition-temperature superconductor Pr0.88LaCe0.12CuO4−_δ_ . _Nature_ 442, 59–62 (2006). Article  CAS  Google Scholar  * Gauthier, J. et al. Different roles of cerium

substitution and oxygen reduction in transport in Pr2−_x_ Ce _x_ CuO4 thin films. _Phys. Rev. B_ 75, 024424 (2007). Article  Google Scholar  * Armitage, N. P. et al. Doping dependence of an

_n_-type cuprate superconductor investigated by angle-resolved photoemission spectroscopy. _Phys. Rev. Lett._ 88, 257001 (2002). Article  CAS  Google Scholar  * Matsui, H. et al. Direct

observation of a nonmonotonic d x 2 - y 2 -wave superconducting gap in the electron-doped high-_T_ c superconductor Pr0.89LaCe0.11CuO4 . _Phys. Rev. Lett._ 95, 017003 (2005). Article  CAS 

Google Scholar  * Smith, M. G., Mathiram, A., Zhou, J., Goodenough, J. B. & Markert, J. T. Electron-doped superconductivity at 40 K in the infinite-layer compound Sr1−_y_ Nd _y_ CuO2 .

_Nature_ 351, 549–551 (1991). Article  CAS  Google Scholar  * Kirimoto, S., Ueda, K., Naito, M. & Imai, T. Superconducting thin films of electron-doped infinite-layer Sr1−_x_ La _x_ CuO2

grown by molecular beam expitaxy. _Physica C_ 378–381, 127–130 (2002). Article  Google Scholar  * Jung, C. U. et al. Synthesis and pinning properties of the infinite-layer superconductor

Sr0.9La0.1CuO2 . _Physica C_ 366, 299–305 (2002). Article  CAS  Google Scholar  Download references ACKNOWLEDGEMENTS We thank K. Attenkofer for the help with the synchrotron X-ray-scattering

experiments at the 11-ID beamline. The X-ray- and neutron-scattering work is supported in part by the US National Science Foundation with grant No. DMR-0453804 and by an award from the

Research Corporation. The PLCCO single-crystal growth at UT is supported by the US DOE BES under contract No. DE-FG02-05ER46202. ORNL is supported by the US DOE grant No. DE-AC05-00OR22725

through UT/Battelle LLC. Work at Argonne was supported by the US DOE under contract No. DE-AC02-06CH11357. The part of the work done in Japan was supported by a Grant-in-Aid for Science

provided by the Japan Society for the Promotion of Science. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Physics and Astronomy, The University of Tennessee, Knoxville,

Tennessee 37996-1200, USA Hye Jung Kang, Pengcheng Dai & Shiliang Li * NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland

20899-8562, USA Hye Jung Kang & Qingzhen Huang * Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742-2115, USA Hye Jung Kang * Neutron

Scattering Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA Pengcheng Dai * Department of Physics and Astronomy, Brigham Young University, Provo, Utah

84602, USA Branton J. Campbell * Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA Peter J. Chupas & Stephan Rosenkranz * Advanced Photon Source,

Argonne National Laboratory, Argonne, Illinois 60439, USA Peter L. Lee * Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan Seiki Komiya & Yoichi Ando

Authors * Hye Jung Kang View author publications You can also search for this author inPubMed Google Scholar * Pengcheng Dai View author publications You can also search for this author

inPubMed Google Scholar * Branton J. Campbell View author publications You can also search for this author inPubMed Google Scholar * Peter J. Chupas View author publications You can also

search for this author inPubMed Google Scholar * Stephan Rosenkranz View author publications You can also search for this author inPubMed Google Scholar * Peter L. Lee View author

publications You can also search for this author inPubMed Google Scholar * Qingzhen Huang View author publications You can also search for this author inPubMed Google Scholar * Shiliang Li

View author publications You can also search for this author inPubMed Google Scholar * Seiki Komiya View author publications You can also search for this author inPubMed Google Scholar *

Yoichi Ando View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS P.D., H.J.K., B.J.C. and S.R. designed the experiment. H.J.K., P.D., B.J.C.,

P.J.C., S.R. and P.L.L. carried out X-ray-scattering experiments. H.J.K. and Q.H. carried out neutron measurements and refinements. H.J.K. carried out ICP measurements. S.L. prepared ceramic

and single crystals of PLCCO and carried out TGA measurements. S.K. and Y.A. also grew single crystals of PLCCO. The paper was written by P.D., H.J.K. and B.J.C., and other co-authors made

comments on the paper. CORRESPONDING AUTHORS Correspondence to Hye Jung Kang or Pengcheng Dai. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing financial interests.

RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Kang, H., Dai, P., Campbell, B. _et al._ Microscopic annealing process and its impact on

superconductivity in _T_′-structure electron-doped copper oxides. _Nature Mater_ 6, 224–229 (2007). https://doi.org/10.1038/nmat1847 Download citation * Received: 20 October 2006 * Accepted:

12 January 2007 * Published: 18 February 2007 * Issue Date: March 2007 * DOI: https://doi.org/10.1038/nmat1847 SHARE THIS ARTICLE Anyone you share the following link with will be able to

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