Angle-resolved photoemission study of untwinned PrBa2Cu3O7: Undoped CuO2 plane and doped CuO3 chain

We have performed an angle-resolved photoemission study on untwinned PrBa2C u3O7, which has low resistivity but does not show superconductivity. We hav e observed a dispersive feature with a band maximum around (pi/2, pi/2), in dicating that this band is derived from the undoped CuO2 plane. We have obs erved another dispersive band exhibiting one-dimensional character, which w e attribute to signals from the doped CuO3 chain. The overall band dispersi on of the one-dimensional band agrees with the prediction of the t-J model calculation with parameters relevant to cuprates except that the intensity near the Fermi level is considerably suppressed in the experiment. [S0163-1 829(99)04541-5].