We have investigated phonons with the inelastic neutron scattering in order to study the 100 K spin-state transition (ST) in LaCoO3. The acoustic phonon dispersions show some characteristic features of the folded Brillouin zone (BZ) of the rhombohedrally distorted perovskite structure containing two chemical formula of LaCoO3 in the unit cell. The optical phonons of the Eg rotational modes of O atoms and the Eg vibration mode of La atoms show a remarkable softening above the ST. The softening is most pronounced at R-point of the pseudo-cubic reciprocal lattice but covers almost whole region of the Brillouin zone. In contrast, the acoustic phonons show no such softening associated with the ST.
- Inelastic neutron scattering
- Spin-state transition
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering