Letter

Nature 442, 59-62 (6 July 2006) | doi:10.1038/nature04857; Received 9 February 2006; Accepted 27 April 2006

Resonance in the electron-doped high-transition-temperature superconductor Pr0.88LaCe0.12CuO4-delta

Stephen D. Wilson1, Pengcheng Dai1,2, Shiliang Li1, Songxue Chi1, H. J. Kang3,4 & J. W. Lynn3

  1. Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA
  2. Center for Neutron Scattering, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  3. NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8562, USA
  4. Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA

Correspondence to: Pengcheng Dai1,2 Correspondence and requests for materials should be addressed to P.D. (Email: daip@ornl.gov).

In conventional superconductors, the interaction that pairs the electrons to form the superconducting state is mediated by lattice vibrations1 (phonons). In high-transition-temperature (high-T c) copper oxides, it is generally believed that magnetic excitations might play a fundamental role in the superconducting mechanism because superconductivity occurs when mobile 'electrons' or 'holes' are doped into the antiferromagnetic parent compounds2. Indeed, a sharp magnetic excitation termed 'resonance' has been observed by neutron scattering in a number of hole-doped materials3, 4, 5, 6, 7, 8, 9, 10, 11. The resonance is intimately related to superconductivity12, and its interaction with charged quasi-particles observed by photoemission13, 14, optical conductivity15, and tunnelling16 suggests that it might play a part similar to that of phonons in conventional superconductors. The relevance of the resonance to high-T c superconductivity, however, has been in doubt because so far it has been found only in hole-doped materials17. Here we report the discovery of the resonance in electron-doped superconducting Pr0.88LaCe0.12CuO4-delta (T c = 24 K). We find that the resonance energy (E r) is proportional to T c via E r approximately 5.8k B T c for all high-T c superconductors irrespective of electron- or hole-doping. Our results demonstrate that the resonance is a fundamental property of the superconducting copper oxides and therefore must be essential in the mechanism of superconductivity.

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