Fermi surface and electronic structure of ${\mathrm{Nd}}_{2\mathrm{-}\mathit{x}}$${\mathrm{Ce}}_{\mathit{x}}$${\mathrm{CuO}}_{4\mathrm{-}\mathrm{\delta }}$

Using angle-resolved photoemission, we have mapped out the Fermi surface (FS) of single crystal ${\mathrm{Nd}}_{2\mathrm{-}\mathit{x}}$ ${\mathrm{Ce}}_{\mathit{x}}$ ${\mathrm{CuO}}_{4\mathrm{-}\mathrm{\delta }}$ when doped as a superconductor (x=0.15) and overdoped as a metal (x=0.22). The measured FS agrees very well with local-density-approximation calculations and appears to shift with electron doping as expected by a band-filling scenario. The observed FS shape suggests that a model Hamiltonian with only nearest-neighbor interactions is not sufficient to describe the electronic structure near ${\mathit{E}}_{\mathit{F}}$; next-nearest-neighbor interactions should be considered.