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Asymmetry of collective excitations in electron- and hole-doped cuprate superconductors


High-temperature superconductivity emerges on doping holes or electrons into antiferromagnetic copper oxides. The large energy scale of magnetic excitations, for example, compared with phonon energies, is thought to drive superconductivity with high transition temperatures (Tc). Comparing high-energy magnetic excitations of hole- and electron-doped superconductors provides an opportunity to test this hypothesis. Here, we use resonant inelastic X-ray scattering at the Cu L3-edge to reveal collective excitations in the electron-doped cuprate Nd2−xCexCuO4. Surprisingly, magnetic excitations harden significantly across the antiferromagnetic high-temperature superconductivity phase boundary despite short-ranged antiferromagnetic correlations, in contrast to the hole-doped cuprates. Furthermore, we find an unexpected branch of collective modes in superconducting compounds, absent in hole-doped cuprates. These modes emanate from the zone centre and possess a higher temperature scale than Tc, signalling a distinct quantum phase. Despite their differences, the persistence of magnetic excitations and the existence of a distinct quantum phase are apparently universal in both hole- and electron-doped cuprates.

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Figure 1: Magnons in antiferromagnetic NCCO (x = 0.04).
Figure 2: Paramagnons and unexpected collective modes in superconducting NCCO (x = 0.147).
Figure 3: Hardening of magnetic excitations.
Figure 4: Doping and temperature dependence of the collective modes.
Figure 5: Distinct doping evolution of the collective excitations in electron- and hole-doped cuprates.


  1. Kastner, M. A., Birgeneau, R. J., Shirane, G. & Endoh, Y. Magnetic, transport, and optical properties of monolayer copper oxides. Rev. Mod. Phys. 70, 897–928 (1998).

    Article  ADS  Google Scholar 

  2. Ghiringhelli, G. et al. Long range incommensurate charge fluctuations in (Y, Bd)Ba2Cu3O6. +x . Science 337, 821–825 (2012).

    Article  ADS  Google Scholar 

  3. Chang, J. et al. Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3O6.67 . Nature Phys. 8, 871–876 (2012).

    Article  ADS  Google Scholar 

  4. Da Silva Neto, E. H. et al. Ubiquitous interplay between charge order and high temperature superconductivity in cuprates. Science 343, 393–396 (2013).

    Article  ADS  Google Scholar 

  5. Comin, R. et al. Charge order driven by Fermi-arc instability in Bi2Sr2−xLaxCuO6+δ . Science 343, 390–392 (2013).

    Article  ADS  Google Scholar 

  6. Li, Y. et al. Unusual magnetic order in the pseudogap region of the superconductor HgBa2CuO4+δ . Nature 455, 372–375 (2008).

    Article  ADS  Google Scholar 

  7. Ament, P. L., van Veenendaal, M., Devereaux, T. P., Hill, J. P. & van den Brink, J. Resonant inelastic x-ray scattering studies of elementary excitations. Rev. Mod. Phys. 83, 705–767 (2011).

    Article  ADS  Google Scholar 

  8. Strocov, V. N. et al. High-resolution soft x-ray beamline ADRESS at the Swiss Light Source for resonant inelastic x-ray scattering and angle-resolved photoelectron spectroscopies. J. Synchrotron Radiat. 17, 631–643 (2010).

    Article  Google Scholar 

  9. Le Tacon, M. et al. Intense paramagnon excitations in a large family of high-temperature superconductor. Nature Phys. 7, 725–730 (2011).

    Article  ADS  Google Scholar 

  10. Dean, M. P.M. et al. Persistence of magnetic excitations in La2−xSrxCuO4 from the undoped insulator to the heavily overdoped non-superconducting metal. Nature Mater. 12, 1019–1023 (2013).

    Article  ADS  Google Scholar 

  11. Takagi, H., Uchida, S. & Tokura, Y. Superconductivity produced by electron doping in CuO2-layered compounds. Phys. Rev. Lett. 62, 1197–1200 (1989).

    Article  ADS  Google Scholar 

  12. Armitage, N. P., Fournier, P. & Greene, R. L. Progress and perspectives on electron-doped cuprates. Rev. Mod. Phys. 82, 2421–2487 (2010).

    Article  ADS  Google Scholar 

  13. Braicovich, L. et al. Momentum and polarization dependence of single-magnon spectral weight for Cu L3-edge resonant inelastic x-ray scattering from layered cuprates. Phys. Rev. B 81, 174533 (2010).

    Article  ADS  Google Scholar 

  14. Guarise, M. et al. Measurement of magnetic excitations in the two-dimensional antiferromagnetic Sr2CuO2Cl2 insulator using resonant x-ray scattering: Evidence for extended interactions. Phys. Rev. Lett. 105, 157006 (2010).

    Article  ADS  Google Scholar 

  15. Bourges, P., Casalta, H., Ivanov, A. S. & Petitgrand, D. Superexchange coupling and spin susceptibility spectral weight in undoped monolayer cuprates. Phys. Rev. Lett. 79, 4906 (1997).

    Article  ADS  Google Scholar 

  16. Motoyama, E. M. et al. Spin correlations in electron-doped high transition-temperature superconductor Nd2−xCexCuO4 . Nature 445, 186–189 (2007).

    Article  ADS  Google Scholar 

  17. Wilson, S. D. et al. High-energy spin excitations in the electron-doped superconductor Pr0.88LaCe0.12CuO4−δ with T c = 21 K. Phys. Rev. Lett. 96, 157001 (2006).

    Article  ADS  Google Scholar 

  18. Fujita, M., Matsuda, M., Fåk, B., Frost, C. D. & Yamada, K. Novel spin excitations in optimally electron-doped Pr0.89LaCe0.11CuO4 . J. Phys. Soc. Jpn 75, 093704 (2006).

    Article  ADS  Google Scholar 

  19. Jia, C. J. et al. Persistent spin excitations in doped antiferromagnets revealed by resonant inelastic light scattering. Nature Commun. 5, 3314 (2014).

    Article  ADS  Google Scholar 

  20. Schmitt, F. et al. Analysis of the spectral function of Nd1.85Ce0.15CuO4 obtained by angle-resolved photoemission spectroscopy. Phys. Rev. B 78, 100505 (2008).

    Article  ADS  Google Scholar 

  21. Singley, E. J., Basov, D. N., Kurahashi, K., Uefuji, T. & Yamada, K. Electron dynamics in Nd1.85Ce0.15CuO4+δ . Phys. Rev. B 64, 224503 (2001).

    Article  ADS  Google Scholar 

  22. Matsui, H. et al. Evolution of the pseudogap across the magnet-superconductor phase boundary of Nd2−xCexCuO4 . Phys. Rev. B 75, 224514 (2007).

    Article  ADS  Google Scholar 

  23. Hinton, J. P. et al. Time-resolved optical reflectivity of the electron-doped Nd2−xCexCuO4+δ cuprate superconductor: Evidence for an interplay between competing orders. Phys. Rev. Lett. 110, 217002 (2013).

    Article  ADS  Google Scholar 

  24. Chakravarty, S., Laughlin, R. B., Morr, D. K. & Nayak, C. Hidden order in the cuprates. Phys. Rev. B 63, 094503 (2001).

    Article  ADS  Google Scholar 

  25. Varma, C. M. Theory of pseudogap state of the cuprates. Phys. Rev. B 73, 155113 (2006).

    Article  ADS  Google Scholar 

  26. Fujita, M. et al. Progress in neutron scattering studies of spin excitations in high-T C cuprates. J. Phys. Soc. Jpn 81, 011007 (2012).

    Article  ADS  Google Scholar 

  27. Broun, D. M. What lies beneath the dome? Nature Phys. 4, 170–172 (2008).

    Article  ADS  Google Scholar 

  28. Vishik, I. M. et al. Phase competition in trisected superconducting dome. Proc. Natl Acad. Sci. USA 109, 18332–18337 (2012).

    Article  ADS  Google Scholar 

  29. Scalapino, D. J. A common thread: The pairing interaction for unconventional superconductors. Rev. Mod. Phys. 84, 1383–1417 (2012).

    Article  ADS  Google Scholar 

  30. Dahm, T. et al. Strength of the spin-fluctuation-mediated pairing interaction in a high-temperature superconductor. Nature Phys. 5, 217–221 (2009).

    Article  ADS  Google Scholar 

  31. Anderson, P. W. Is there glue in cuprate superconductors? Science 316, 1705–1707 (2007).

    Article  Google Scholar 

  32. Lai, C. H. et al. High efficient beamline and spectrometer for inelastic soft x-ray scattering at high resolution. J. Sync. Rad. 21, 325–332 (2014).

    Article  Google Scholar 

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The authors appreciate Y. Lu’s support in characterizing the doping levels of the measured samples. This work was supported by the US Department of Energy, Office of Basic Energy Science, Division of Materials Science and Engineering under contract no. DE-AC02-76SF00515. The work at University of Minnesota was supported by the NSF and the NSF MRSEC program. S.G. acknowledges support from the Swiss NSF (Contract No. P2EZP2_148737). The authors appreciate the experimental support from the ADRESS beamline of the Swiss Light Source (SLS) at the Paul Scherrer Institut, Switzerland and the beamline BL05A1 at the National Synchrotron Radiation Research Center (NSRRC), Taiwan.

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Authors and Affiliations



W.S.L. conceived and designed the experiments with suggestions from Z.X.S., M.G., T.P.D. and T.S.; W.S.L., J.J.L., W.T., S.G., S.W.H., Y.B.H., V.N.S. and T.S. performed the measurement at the SLS; W.S.L., H.Y.H., R.P.W., W.B.W., C.T.C. and D.J.H. performed the measurement at the NSRRC. E.M.M., G.Y. and M.G. synthesized and prepared the single-crystals used for the measurements. E.A.N., B.M. and T.P.D. performed the theoretical calculations. W.S.L. wrote the manuscript with contributions from all authors.

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Correspondence to W. S. Lee, Z. X. Shen or T. P. Devereaux.

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The authors declare no competing financial interests.

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Lee, W., Lee, J., Nowadnick, E. et al. Asymmetry of collective excitations in electron- and hole-doped cuprate superconductors. Nature Phys 10, 883–889 (2014).

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