Electronic Structure of Electron-doped Sm$_{1.86}$Ce$_{0.14}$CuO$_{4}$ : Strong `Pseudo-Gap' Effects and Nodeless Gap

Angle resolved photoemission (ARPES) data from the electron doped cuprate superconductor Sm$_{1.86}$Ce$_{0.14}$CuO$_{4}$ shows a much stronger pseudo-gap or ``hot-spot" effect than that observed in other optimally doped n-type cuprates. Importantly, these effects are strong enough to drive the zone-diagonal states below the chemical potential, implying that d-wave superconductivity in this compound would be of a novel ``nodeless" gap variety. The gross features of the Fermi surface topology and low energy electronic structure are found to be well described by reconstruction of bands by a root 2 times root 2 order. Comparison of the ARPES and optical data from the same sample shows that the pseudo-gap energy observed in optical data is consistent with the inter-band transition energy of the model, allowing us to have a unified picture of pseudo-gap effects.