  The asymmetry between electron and hole doping remains one of the central
issues in high-temperature cuprate superconductivity, but our understanding of
the electron-doped cuprates has been hampered by apparent discrepancies between
the only two known families: Re2-xCexCuO4 and A1-xLaxCuO2. Here we report in
situ angle-resolved photoemission spectroscopy measurements of
epitaxially-stabilized films of Sr1-xLaxCuO2 synthesized by oxide
molecular-beam epitaxy. Our results reveal a strong coupling between electrons
and (pi,pi) antiferromagnetism that induces a Fermi surface reconstruction
which pushes the nodal states below the Fermi level. This removes the hole
pocket near (pi/2,pi/2), realizing nodeless superconductivity without requiring
a change in the symmetry of the order parameter and providing a universal
understanding of all electron-doped cuprates.
