Electronic-structure evolution through the metal-insulator transition in RNiO3

We performed a photoemission investigation of the electronic structure of PrNiO3 and NdNiO3 through the first order (paramagnetic) metal to (antiferromagnetic) insulator transition. Surprisingly, the data reveal a temperature-dependent loss of spectral weight near the chemical potential, which extends well below the coincident metal-insulator (TMI) and magnetic (TNéel) transition temperatures. This is in contrast with the behavior in SmNiO3 and EuNiO3, where the two transitions are separate. The spectral properties clearly indicate two distinct regimes for RNiO3 with TMI=TNéel and TMI>TNéel.