Low temperature mixed spin state of Co3+ in LaCoO3 evidenced from Jahn-Teller lattice distortions

Abstract

One- and multi-phonon excitations of the single crystalline LaCoO3 were studied using Raman spectroscopy in the temperature region of 5 K - 300 K. First-order Raman spectra show a larger number of phonon modes than allowed for the rhombohedral structure. Additional phonon modes are interpreted in terms of activated modes due to lattice distortions, arising from the Jahn-Teller (JT) activity of the intermediate-spin (IS) state of Co3+ ions. In particular, the 608-cm-1 stretching-type mode shows anomalous behavior in peak energy and scattering intensity as a function of temperature. The anomalous temperature dependence of the second-order phonon excitations spectra is in accordance with the Franck-Condon mechanism that is characteristic for a JT orbital order.

11 pages, 9 figures, to be published in J. Low. Temp. Physics

References in corpus (6)

• Structural phenomena associated with the spin-state transition in LaCoO3
• Evidence for a Low-Spin to Intermediate-Spin State Transition in LaCoO3
• Evidence for orbital ordering in LaCoO3
• Self-trapped Exciton and Franck-Condon Spectra Predicted in LaMnO${}_3$
• Multi-phonon Resonant Raman Scattering Predicted in LaMnO3 from the Franck-Condon Process via Self-Trapped Excitons
• Orbiton-mediated multi-phonon scattering in La${}_{1-x}$Sr${}_x$MnO${}_3$

Cited by in corpus (3)

• Local Structure of La1-xSrxCoO3 determined from EXAFS and neutron PDF studies
• Role of Entropy and Structural Parameters in the Spin State Transition of LaCoO${}_3$
• DFT+DMFT study of spin-charge-lattice coupling in covalent LaCoO${}_3$