Angle-resolved photoemission from ${\mathrm{Nd}}_{2\mathrm{-}\mathit{x}}$${\mathrm{Ce}}_{\mathit{x}}$${\mathrm{CuO}}_4$(001): A dispersive bandlike Fermi-liquid state of Cu 3d character near the Fermi level

The electronic structure of ${\mathrm{Nd}}_{2\mathrm{-}\mathit{x}}$ ${\mathrm{Ce}}_{\mathit{x}}$ ${\mathrm{CuO}}_4$(001) single-crystal thin films, which show (1×1) low-energy electron diffraction patterns, has been studied by angle-resolved ultraviolet photoemission spectroscopy with synchrotron radiation. The data show a well-defined but resolution-limited Fermi edge with a maximum intensity of more than 6% as compared to the main peak intensity. The main peaks exhibit ill-defined dispersion of less than 0.4 eV. All in all, the band calculation can describe the experimental spectra to a fair degree. We find a dispersive bandlike Fermi-liquid state of dominant Cu 3d character (almost no O 2p and Cu 4s character) just below the Fermi level. Its dispersion of 0.2 eV is 8–10 times smaller than that expected from the band calculation. These facts indicate that there is a possibility of Kondo-type renormalized heavy-electron band formation at the Fermi level, caused by spin fluctuations.