ARPES/STM study of the surface terminations and 5 f-electron character in URu₂Si₂

Hidden order in URu₂Si₂ has remained a mystery that is now entering its fourth decade. The importance of resolving the nature of the hidden order has stimulated extensive research. Here we present a detailed characterization of different surface terminations in URu₂Si₂ by angle-resolved photoemission spectroscopy, in conjunction with scanning tunneling spectroscopy and dynamical mean-field theory calculations that may unveil a piece of this puzzle. The U-terminated surface is characterized by an electronlike band around the X point, while a holelike band characterizes the Si-terminated surface. We also investigate the temperature evolution of the electronic structure around the X point from 11 up to 70 K, and do not observe any abrupt change of the electronic structure around the coherence temperature (55 K). Our results suggest that surface terminations in URu₂Si₂ are an important issue to be taken into account in future work.