Evolution of the Fermi Surface of the Electron-Doped High-Temperature Superconductor Nd2-xCexCuO4 Revealed by Shubnikov-de Haas Oscillations

We report on the direct probing of the Fermi surface in the bulk of the electron-doped superconductor Nd2-xCexCuO4 at different doping levels by means of magnetoresistance quantum oscillations. Our data reveal a sharp qualitative change in the Fermi surface topology, due to translational symmetry breaking in the electronic system which occurs at a critical doping level significantly exceeding the optimal doping. This result implies that the (pi/a, pi/a) ordering, known to exist at low doping levels, survives up to the overdoped superconducting regime.