The low-energy excitations of the lightly doped cuprates were studied by angle-resolved photoemission spectroscopy. A finite gap was measured over the entire Brillouin zone, including along the dx2-y2 nodal line. This effect was observed to be generic to the normal states of numerous cuprates, including hole-doped La2-xSrxCuO4 and Ca2-xNaxCuO2Cl2 and electron-doped Nd2-xCexCuO4. In all compounds, the gap appears to close with increasing carrier doping. We consider various scenarios to explain our results, including the possible effects of chemical disorder, electronic inhomogeneity, and a competing phase.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2004 2月 17|
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