Neutron scattering study on electron-hole doping symmetry of high-Tc superconductivity

We review recent results of neutron scattering experiment on spin correlations for both hole-doped La2-xSr2CuO4+y and electron-doped Nd1.85Ce0.15CuO4+y superconductors, For the former, hole-doping induces an incommensurate spin density modulation along the Cu-O bonds. For the latter, we observed well-defined spin fluctuations in the superconducting phase (T-c approximate to 18 K) for the first time. In contrast to the hole-doping, the electron-doping induces no well-defined incommensurate spin modulation; the magnetic signal appears at ( pi, pi) with a q-width broader than in the as-grown antiferromagnetic phase. For both systems a static magnetic order was observed in the superconducting state. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.