Electronic structure as a function of doping in YBa{sub 2}Cu{sub 3}O{sub {ital x}}(6.2{le}{ital x}{le}6.9) studied by angle-resolved photoemission

We report angle-resolved photoemission studies on YBa{sub 2}Cu{sub 3}O{sub {ital x}} with oxygen stoichiometry varied in the range 6.2{le}{ital x}{le}6.9. The distinct 1-eV peak, observed with {ital h}{nu}=24 eV at the {ital X}({ital Y}) point(s), shifts monotonically toward higher binding energies (as much as 0.20 eV) as oxygen stoichiometry is reduced from {ital x}=6.9 to 6.3. The direction and the magnitude of the shift are consistent with a simple rigid-band filling picture. However, another distinct peak observed at the {ital X}({ital Y}) point(s), but with energy very close to {ital E}{sub {ital F}}, remains at nearly the same energy when the oxygen stoichiometry is varied from 6.9 to 6.4. This behavior is not consistent with a rigid-band picture. The intensities of the 1-eV peak and the peak at {ital E}{sub {ital F}} are significantly attenuated when the material becomes insulating.