We present an angle resolved photoemission (ARPES) doping dependence study of the n-type cuprate superconductor Nd_2-xCe_xCuO_4, from the half-filled Mott-insulator to the T_c=24K superconductor. In Nd2CuO4, we reveal the charge-transfer band (CTB) for the first time. As electrons are doped into the system, this feature's intensity decreases with the concomitant formation of near-E_F spectral weight. At low doping, the Fermi surface is an electron-pocket (with volume ~ x) centered at (pi,0). Further doping leads to the creation of a new hole-like Fermi surface (volume ~ 1+x) centered at (pi,pi). These findings shed light on the Mott gap, its doping evolution, as well as the anomalous transport properties of the n-type cuprates.
@article{arxiv.cond-mat/0201119,
title = {Doping dependence of an n-type cuprate superconductor investigated by ARPES},
author = {N. P. Armitage and F. Ronning and D. H. Lu and C. Kim and A. Damascelli and K. M. Shen and D. L. Feng and H. Eisaki and Z. -X. Shen and P. K. Mang and N. Kaneko and M. Greven and Y. Onose and Y. Taguchi and Y. Tokura},
journal= {arXiv preprint arXiv:cond-mat/0201119},
year = {2009}
}