Speaker
Dariusz Jakub Gawryluk
(Paul Scherrer Institut)
Description
RNiO$_3$ perovskites (R = rare earth, Tl$^{3+}$, Pb$^{3+}$ or Bi$^{3+}$) display a metal to insulator transition (MIT) at temperatures T$_{MIT}$ than increase by decreasing the lanthanide ionic radius. The electronic localization is associated to a charge disproportionation of the type 2Ni$^{3+}$ = Ni$^{3+d}$ + Ni$^{3-d}$ and with subtle structural distortions related to the Ni$^{3+d}$/Ni$^{3-d}$ charge order. Using neutron powder diffraction the lattice anomalies of PrNiO$_3$ have been re-investigated and interpreted in terms of “frozen” normal distortion modes1. We identify a new breathing mode with non-zero amplitude below T$_{MIT}$ and associate it to the charge order responsible for the MIT.
Primary author
Dariusz Jakub Gawryluk
(Paul Scherrer Institut)
Co-authors
Dr
Juan Rodríguez-Carvajal
(Institut Laue-Langevin)
Dr
Maria Teresa Fernández-Díaz
(Institut Laue-Langevin)
Prof.
Philippe Lacorre
(UFR Sciences et Techniques, Université du Maine)
Marisa Medarde
(Paul Scherrer Institut)
