Electronic structure of URu2Si2 in paramagnetic phase: three-dimensional angle resolved photoelectron spectroscopy study

The three-dimensional (3D) electronic structure of the hidden order compound URu2Si2 in a paramagnetic phase was revealed using a 3D angle-resolved photoelectron spectroscopy where the electronic structure of the entire Brillouin zone is obtained by scanning both incident photon energy and detection angles of photoelectrons. The quasi-particle bands with enhanced contribution from the U5f state were observed near EF, formed by the hybridization with the Ru 4d states. The energy dispersion of the quasi-particle band is significantly depend on kz, indicating that they inherently have a 3D nature. The band-structure calculation qualitatively explain the characteristic features of the band structure and Fermi surface although the electron correlation effect strongly renormalizes the quasi-particle bands. The 3D and strongly-correlated nature of the quasi-particle bands in URu2Si2 is an essential ingredient for modeling its hidden-order transition.