We use inelastic neutron scattering to probe magnetic excitations of an optimally electron-doped superconductor Nd1.85Ce0.15CuO4−δ above and below its superconducting transition temperature Tc=25 K. In addition to gradually opening a spin pseudo gap at the antiferromagnetic ordering wavevector Q=(1/2,1/2,0), the effect of superconductivity is to form a resonance centered also at Q=(1/2,1/2,0) but at energies above the spin pseudo gap. The intensity of the resonance develops like a superconducting order parameter, similar to those for hole-doped superconductors and electron-doped Pr0.88LaCe0.12CuO4. The resonance is therefore a general phenomenon of cuprate superconductors, and must be fundamental to the mechanism of high-Tc superconductivity.
@article{arxiv.cond-mat/0703732,
title = {Resonance in Optimally Electron-Doped Superconductor Nd$_{1.85}$Ce$_{0.15}$CuO$_{4-\delta}$},
author = {Jun Zhao and Pengcheng Dai and Shiliang Li and Paul G. Freeman and Y. Onose and Y. Tokura},
journal= {arXiv preprint arXiv:cond-mat/0703732},
year = {2009}
}