ARPES study of quasiparticle state in electron-doped cuprate Nd2−xCexCuO4

We report high-resolution angle-resolved photoemission spectroscopy on electron-doped cuprate Nd2−xCexCuO4 to study the quasiparticle (QP) state in the vicinity of the Fermi level. Measurements of momentum dependence have revealed that the mass-renormalized QP state around (π, 0) continuously evolves into the high-energy correlation gap, which opens at the intersecting point of the Fermi surface and the magnetic zone boundary. We also observed that the QP spectrum shows remarkable temperature and Ce-concentration dependence in accordance with the spin correlation. These results indicate that the heavy-mass QP state in the electron-doped cuprate originates in the antiferromagnetic order/fluctuation.