Phase transition arising from the underscreened Anderson lattice model: A candidate concept for explaining hidden order in URu2Si2

We analyze a type of phase transition that appears in the spin-rotationally invariant form of the underscreened Anderson lattice model and we obtain, with decreasing temperature, a continuous transition with the opening of a gap. We suggest that this model might describe the hidden-order transition in URu2Si2. We also examine the gaps that appear in the electronic dispersion relations of the bands of different orbital character and compare our results with those found through photoelectron spectroscopy.