CM-AMO Seminar | N-point van Hove singularity origin of the Hidden Order phase of URu2Si2

The 5f heavy fermion system of URu2Si2 is famous for an unconventional “hidden order” (HO) phase transition at T0=17.5K that has been a topic of study for 35 years. A new model is proposed for the underlying physics to be the existence of a van Hove singularity saddle-band dispersion at the Brillouin zone N-point that is only a few meV below the Fermi level, and thus thermally active at T0. The new model, based on temperature-dependent angle resolved photoemission (ARPES) measurements in comparison to DMFT electronic structure calculations [1], is further confirmed by additional ARPES observation of the N-point spectral and dichroic changes for various chemically doped phases with different ferromagnetic, antiferromagnetic or non-magnetic ground states.

[1] J. D. Denlinger et al., Electron. Struct. 4, 013001 (2022).