  In the hole-doped cuprates, a small amount of carriers suppresses
antiferromagnetism and induces superconductivity. In the electron-doped
cuprates, on the other hand, superconductivity appears only in a narrow range
of high electron concentration ($\sim$ doped Ce content) after reduction
annealing, and strong antiferromagnetic (AFM) correlation persists in the
superconducting phase. Recently, Pr$_{1.3-x}$La$_{0.7}$Ce$_{x}$CuO$_{4}$
(PLCCO) bulk single crystals annealed by a "protect annealing" method showed a
high $T_c$ of $\sim$ 27 K for small Ce content down to $x \sim 0.05$. By
angle-resolved photoemission spectroscopy (ARPES) measurements of PLCCO
crystals, we observed a sharp quasi-particle peak on the entire Fermi surface
without signature of an AFM pseudogap unlike all the previous work, indicating
a dramatic reduction of AFM correlation length and/or of magnetic moments. The
superconducting state was found to extend over a wide electron concentration
range. The present ARPES results fundamentally change the long-standing picture
on the electronic structure in the electron-doped regime.
