Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 47: Correlated Electrons: Other Materials
TT 47.1: Vortrag
Mittwoch, 9. März 2016, 10:30–10:45, H23
Phonon renormalization in LaCoO3 by inelastic neutron and x-ray scattering — •Maximilian Kauth1, Frank Weber1, and John-Paul Castellan1,2 — 1Institut für Festkörperphysik, Karlsruher Institut für Technologie — 2Laboratoire Léon Brillouin, CEA Saclay
LaCoO3 exhibits two broad magnetic-electric transitions, a diamagnetic to paramagnetic spin-state transition at TSS≈ 100 K and a metal-insulator transition at TMI≈ 500 K. The spin transitions on heating are proposed to be as follows [1]: from a homogeneous LS state to a mixed Low-Spin/High-Spin (LS/HS) state with strong spin-charge fluctuations at T=TSS and, subsequently, into a homogeneous HS state at T=TMI. The lattice participates in the state mixture by expansion of CoO6 octahedra around the HS sites, while the ones around LS sites have a reduced size [2]. The originally proposed static order [2] has not been observed experimentally and, hence, the ordering is expected to be dynamic and short-ranged.
We investigated the lattice dynamical properties of LaCoO3 using inelastic neutron scattering. Based on detailed ab-initio lattice dynamical calculations (performed in our institute), we aim for a comprehensive understanding of lattice dynamics in LaCoO3. The above discussed crossovers and spin state order should be reflected in the lattice degrees of freedom via quasi elastic scattering and phonon renormalization effects.
M. Karolak et al., PRL 115, 046401 (2015)
J. B. Goodenough, J. Phys. Chem. Solids 6, 287 (1958)