Band structure and Fermi surface of URu₂Si₂ studied by high-resolution angle-resolved photoemission spectroscopy

We have performed a high-resolution angle-resolved photoemission spectroscopy (ARPES) on single-crystal URu₂Si₂ to study the band structure and the Fermi surface in the paramagnetic phase. The valence-band structure consisting of the Ru 4d and Si 3p states shows a qualitatively good agreement between the ARPES experiment and the band-structure calculation. In the vicinity of the Fermi level (E_F), we observed a less dispersive band, which crosses E_F midway between the Z and X points in the Brillouin zone. Comparison with the band calculation as well as with the de Haas-van Alphen (dHvA) result suggests that the experimental band near E_F is assigned to the largest hole pocket centered at the Z point, which has a strong U 5f-Ru4d hybridized character. The observed remarkable narrowing of the near-E_F band compared with the band-structure calculation suggests a strong renormalization effect due to the electron correlation of U 5f electrons.