Anomalous expansion and phonon damping due to the Co spin-state transition in RCoO_3 with R = La, Pr, Nd and Eu

Abstract

We present a combined study of the thermal expansion and the thermal conductivity of the perovskite series RCoO_3 with R = La, Nd, Pr and Eu. The well-known spin-state transition in LaCoO_3 is strongly affected by the exchange of the R ions due to their different ionic radii, i.e. chemical pressure. This can be monitored in detail by measurements of the thermal expansion, which is a highly sensitive probe for detecting spin-state transitions. The Co ions in the higher spin state act as additional scattering centers for phonons, therefore suppressing the phonon thermal conductivity. Based on the analysis of the interplay between spin-state transition and heat transport, we present a quantitative model of the thermal conductivity for the entire series. In PrCoO_3, an additional scattering effect is active at low temperatures. This effect arises from the crystal field splitting of the 4f multiplet, which allows for resonant scattering of phonons between the various 4f levels.

15 pages including 5 figures

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Cited by in corpus (7)

• Spin state transition and covalent bonding in LaCoO3
• Spin state transition in LaCoO3 by variational cluster approximation
• DFT+DMFT study of spin-charge-lattice coupling in covalent LaCoO${}_3$
• Phase diagram and isotope effect in (PrEu)_0.7Ca_0.3CoO_3 cobaltites exhibiting spin-state transitions
• Effect of Eu doping and partial oxygen isotope substitution on magnetic phase transitions in (Pr${}_{1-y}$Eu${}_y$)${}_{0.7}$Ca${}_{0.3}$CoO${}_3$ cobaltites
• Spin-state transition, magnetism and local crystal structure in Eu_{1-x}Ca_xCoO_{3-d}
• Heat conductivity of the spin-Peierls compounds TiOCl and TiOBr