Evolution of the Fermi Surface of the Electron-Doped High-Temperature Superconductor Nd_2-xCe_xCuO₄ Revealed by Shubnikov–de Haas Oscillations

We report on the direct probing of the Fermi surface in the bulk of the electron-doped superconductor Nd_2-xCe_xCuO₄ 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 (π/a, π/a) ordering, known to exist at low doping levels, survives up to the overdoped superconducting regime.