Abrupt electronic structure changes in URu$_{2}$Si$_{2}$ at the Hidden Order transition

In recent years, high-resolution angle-resolved photoemission (ARPES) measurements of URu$_{2}$Si$_{2}$ [1] have attempted to characterized the temperature dependent behavior of $f$-states close to the Fermi level in the range of photon energies of 7-31 eV and in a narrow $k$-space range around the surface zone center revealing varying ways in which energy shifts, backfolding of states and/or spectral weight sharpening correlate to the hidden order transition at 17.5K. In this study we expand the temperature dependent ARPES measurements to a broader range of photon energy and emission angles in order to probe the full 3-dimensional electronic structure. We find particular $k$-space regions close to incommensurate wave vector separation that exhibit dramatic electronic structure changes that are abrupt at the hidden order transition and whose evolution to higher temperatures correlates to a gradual Kondo coherence transition below $\sim$50K. A critical assessment of these electronic structure changes in relation to LDA band structure predictions is discussed. \\[4pt] [1] A.F. Santander-Syro, Nat. Phys. 2009; R. Yoshida, PRB 2010; G.L. Dakovski, PRB 2011; F.L. Boariu, PRL 2013; S. Chatterjee, PRL 2013; J.Q. Meng, PRL 2013.