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Superconductivity in CaCuO2 as a result of field-effect doping

A Retraction to this article was published on 06 March 2003


Understanding the doping mechanisms in the simplest superconducting copper oxide—the infinite-layer compound ACuO2 (where A is an alkaline earth metal)—is an excellent way of investigating the pairing mechanism in high-transition-temperature (high-Tc) superconductors more generally1,2,3,4. Gate-induced modulation of the carrier concentration5,6,7 to obtain superconductivity is a powerful means of achieving such understanding: it minimizes the effects of potential scattering by impurities, and of structural modifications arising from chemical dopants. Here we report the transport properties of thin films of the infinite-layer compound CaCuO2 using field-effect doping. At high hole- and electron-doping levels, superconductivity is induced in the nominally insulating material. Maximum values of Tc of 89 K and 34 K are observed respectively for hole- and electron-type doping of around 0.15 charge carriers per CuO2. We can explore the whole doping diagram of the CuO2 plane while changing only a single electric parameter, the gate voltage.

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Figure 1: Schematic structure of the infinite-layer compound CaCuO2.
Figure 2: Structure of the field-effect device.
Figure 3: Resistance of a CaCuO2 film as a function of temperature and electron-doping level x.
Figure 4: Resistivity of a CaCuO2 film as a function of temperature and hole-doping level x.
Figure 5: The superconducting phase diagram of CaCuO2.
Figure 6: Normalized resistance as a function of temperature for n-type under-doped, optimally doped and overdoped CaCuO2.


  1. Smith, M. G., Manthiram, A., Zhou, J., Goodenough, J. B. & Markert, J. T. Electron-doped superconductivity at 40 K in the infinite-layer compound Sr1-yNdyCuO2. Nature 351, 549–551 (1991).

    Article  ADS  CAS  Google Scholar 

  2. Azuma, M., Hiroi, Z., Takano, M., Bando, Y. & Takeda, Y. Superconductivity at 110 K in the infinite-layer compound (Sr1-xCax)1-yCuO2. Nature 356, 775–776 (1992).

    Article  ADS  CAS  Google Scholar 

  3. Zhang, H. et al. Identity of planar defects in the infinite-layer copper oxide superconductor. Nature 370, 352–354 (1994).

    Article  ADS  CAS  Google Scholar 

  4. Laguës, M. et al. in Coherence in High Temperature Superconductors (eds Deutscher, G. & Revcoleschi, A.) 70–98 (World Scientific, Singapore, 1996).

    Google Scholar 

  5. Schön, J. H., Kloc, Ch., Haddon, R. C. & Batlogg, B. A superconducting field-effect switch. Science 288, 656–658 (2000).

    Article  ADS  Google Scholar 

  6. Schön, J. H., Kloc, Ch. & Batlogg, B. Superconducting at 52 K in hole-doped C60. Nature 408, 549–552 (2000).

    Article  ADS  Google Scholar 

  7. Ahn, C. H. et al. Electrostatic modulation of superconductivity in ultrathin GdBa2Cu3O7-x films. Science 294, 1152–1155 (1999).

    Article  ADS  Google Scholar 

  8. Siegrist, T., Zahurak, S. M., Murphy, D. W. & Roth, R. S. The parent structure of the layered high-temperature superconductors. Nature 334, 231–232 (1988).

    Article  ADS  CAS  Google Scholar 

  9. Gupta, A. Growth and properties of thin films of the doped infinite-layer compounds Ca1-xLnxCuO2 (Ln = Sm, Nd, Y). Physica C 231, 389–394 (1994).

    Article  ADS  CAS  Google Scholar 

  10. Lombardi, A., Mali, M., Roos, J., Brinkman, D. & Mangelschots, I. Temperature dependence of the sublattice magnetization of the antiferromagnet Ca0.85Sr0.15CuO2. Phys. Rev. B 54, 93–96 (1996).

    Article  ADS  CAS  Google Scholar 

  11. Er, G., Miyamoto, Y., Kanamuru, F. & Kikkawa, S. Superconductivity in the infinite-layer compound Sr1-xLaxCuO2 prepared under high pressure. Physica C 181, 206–208 (1991).

    Article  ADS  CAS  Google Scholar 

  12. Wooten, C. L. et al. The pressure dependence of Tc in the infinite-layer electron-doped compound Sr0.84Nd0.16CuO2. Physica C 192, 13–17 (1992).

    Article  ADS  CAS  Google Scholar 

  13. Korczak, W., Peroux, M. & Strobel, P. Superconductivity in Sr0.85La0.15CuO2. Physica C 193, 303–308 (1992).

    Article  ADS  CAS  Google Scholar 

  14. Ikeda, N., Hiroi, Z., Azuma, M., Takano, M. & Bando, Y. Synthesis and superconducting properties of the infinite-layer compounds Sr1-xLnxCuO2 (Ln = La, Nd, Sm, Gd). Physica C 210, 367–372 (1993).

    Article  ADS  CAS  Google Scholar 

  15. Niu, C. & Lieber, C. M. Growth of the infinite layer phase of Sr1-xNdxCuO2 by laser ablation. Appl. Phys. Lett. 61, 1712–1714 (1992).

    Article  ADS  CAS  Google Scholar 

  16. Adachi, H., Satoh, T., Ishikawa, Y., Setsune, K. & Wase, K. Superconducting (Sr,Nd)CuOy thin films with infinite-layer structure. Physica C 196, 14–16 (1992).

    Article  ADS  CAS  Google Scholar 

  17. Xie, X. M. et al. Transport mechanisms in infinite layer compounds grown by molecular beam epitaxy. Appl. Phys. Lett. 67, 1671–1673 (1995).

    Article  ADS  CAS  Google Scholar 

  18. Hiroi, Z., Azuma, M., Takano, M. & Takeda, Y. Structure and superconductivity of the infinite-layer compound (Ca1-ySry)1-xCuO2-z. Physica C 208, 286–296 (1993).

    Article  ADS  Google Scholar 

  19. Prouteau, C., Strobel, P., Capponi, J. J., Chaillout, C. & Tholence, J. L. Optimization of superconductivity in the high-pressure Sr-Ca-Cu-O system. Physica C 228, 63–72 (1994).

    Article  ADS  CAS  Google Scholar 

  20. Shaked, H. et al. Superconductivity in the Sr-Ca-Cu-O system and the phase with infinite-layer structure. Phys. Rev. B 51, 11784–11790 (1995).

    Article  ADS  CAS  Google Scholar 

  21. Feenstra, R. et al. Electron-doped and hole-doped infinite layer Sr1-xCuO2-δ films grown by laser molecular beam epitaxy. Physica C 224, 300–316 (1994).

    Article  ADS  CAS  Google Scholar 

  22. Zhou, X., Yao, Y. S., Jia, S. J., Dong, C. & Zhao, Z. Stability and doping of infinite-layer compound (Ca1-xSrx)CuO2 at ambient pressure. J. Mater. Sci. 30, 952–954 (1995).

    Article  Google Scholar 

  23. Vailionis, A., Brazdeikis, A. & Flodström, A. S. Observation of local oxygen displacements in CuO2 planes induced by a misfit strain in heteroepitaxially grown infinite-layer-structure (Ca1-xSrx)CuO2 films. Phys. Rev. B 55, R6152–R6155 (1997).

    Article  ADS  CAS  Google Scholar 

  24. Kopnin, E. M. et al. Ca1-xRxCuO2 (R = Sr, La) single crystals with infinite-layer structure: high Ar gas pressure synthesis and properties. Physica C 282–287, 483–484 (1997).

    Article  ADS  Google Scholar 

  25. Norton, D. P. et al. Superconductivity in SrCuO2-BaCuO2 superlattices: formation of artificially layered superconducting materials. Science 265, 2074–2077 (1994).

    Article  ADS  CAS  Google Scholar 

  26. Balestrino, G., Martellucci, S., Medaglia, P. G., Paoletti, A. & Petrocelli, G. Dependence of the critical temperature on n in (BaCuO2)2/(CaCuO2)n superlattices. Phys. Rev. B 58, R8925–R8928 (1998).

    Article  ADS  CAS  Google Scholar 

  27. Ahn, C. H. et al. Ferroelectric field effect in epitaxial thin film oxide SrCuO2/Pb(Zr0.52Ti0.48)O3 heterostructures. Science 269, 373–376 (1995).

    Article  ADS  CAS  Google Scholar 

  28. Kawahara, T., Sugiuchi, N., Komai, E., Terashima, T. & Bando, Y. Hole and electron doping in ultrathin films with the infinite layer structure by the electric field effect. Physica C 276, 127–131 (1997).

    Article  ADS  CAS  Google Scholar 

  29. Schön, J. H., Berg, S., Kloc, Ch. & Batlogg, B. Ambipolar pentacene field-effect transistors and inverters. Science 287, 1022–1024 (2000).

    Article  ADS  Google Scholar 

  30. Maple, M. B. High-temperature superconductivity. J. Magn. Magn. Mater. 177–181, 18–30 (1998).

    Article  ADS  Google Scholar 

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We thank G. Blumberg, Ch. Kloc, H. Y. Hwang and C. M. Varma for discussions.

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Correspondence to J. H. Schön.

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Schön, J., Dorget, M., Beuran, F. et al. Superconductivity in CaCuO2 as a result of field-effect doping. Nature 414, 434–436 (2001).

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