Séminaire DQMP informel - Recent progress in (bulk) nickelate research

15.12.2017 11:00 – 12:15

RNiO3 perovskite nickelates, (R = rare earth) are one of the few oxide families intrinsically close to the boundary between itinerant and localized behavior. With the exception of metallic LaNiO3, all members of the family display metal-to-insulator transitions at temperatures ranging between 130 K (R=Pr) to 600 K (R=Lu). Although the existence of this transition is known since 1991 [2], the mechanism of the gap opening is not yet fully understood and has been a matter of controversy since its discovery. The availability of high quality thin films has been the key of the enormous progress made during the last 15 years. However, many questions requiring the availability of bulk samples remain unanswered due to the difficulties associated to the high oxygen pressure synthesis procedure.
In this talk I will present some recent progress in the synthesis of nickelate ceramics and single crystals, made possible by the availability of two new high-pressure synthesis systems in our laboratory at the Paul Scherrer Institute. To illustrate the new possibilities open by the availability of such samples I will present novel neutron powder diffraction investigations on the lattice anomalies of PrNiO3 across TMI and its interpretation in terms of “frozen” normal distortion modes. I will also discuss the two proposed models for the Ni magnetic structure on the light of our new experimental results.

Lieu

Bâtiment: Ecole de Physique

MaNEP conference room

entrée libre