Symmetry-resolved elastic anomalies in spin-crossover cobaltite LaCoO${}_3$

Abstract

Ultrasound velocity measurements of the pseudo-cubic spin-crossover cobaltite LaCoO${}_3$ and the lightly Ni-substituted La(Co${}_{0.99}$Ni${}_{0.01}$)O${}_3$ reveal two types of symmetry-resolved elastic anomaly in the insulating paramagnetic state that are commonly observed in these compounds. The temperature dependence of the bulk modulus exhibits Curie-type softening upon cooling below 300 K down to $\sim$70 K, indicating the presence of isostructural lattice instability arising from orbital fluctuations. The temperature dependence of the tetragonal and trigonal shear moduli exhibits unusual hardening upon cooling below 300 K, indicating the occurrence of elasticity crossover arising from the spin crossover. The present study also reveals that the isostructural lattice instability in LaCoO${}_3$ is sensitively suppressed with the Ni substitution, indicating the suppression of orbital fluctuations with the light Ni substitution. This Ni substitution effect in LaCoO${}_3$ can be explained on the basis that the isostructural lattice instability arises from the coupling of the lattice to the Co spin state fluctuating between the high-spin state and intermediate-spin state.

arXiv comment7 pages, 5 figures

References in corpus (20)

• The spin state transition in LaCoO${}_3$; revising a revision
• Spin-state transition in LaCoO3: direct neutron spectroscopic evidence of excited magnetic states
• Nano-magnetic droplets and implications to orbital ordering in La1-xSrxCoO3
• The 5D term origin of the excited triplet in LaCoO3
• Avoided Valence Transition in a Plutonium Superconductor
• Coulomb correlations intertwined with spin and orbital excitations in LaCoO${}_3$
• Jahn-Teller Inactivity and Magnetic Frustration in GeCo${}_2$O${}_4$ Probed by Ultrasound Velocity Measurements
• Elastic Instabilities within Antiferromagnetically Ordered Phase in the Orbitally-Frustrated Spinel GeCo${}_2$O${}_4$
• Two Spin-State Crystallizations in LaCoO${}_3$
• Observation of elastic anomalies driven by coexisting dynamical spin Jahn-Teller effect and dynamical molecular spin state in paramagnetic phase of the frustrated MgCr${}_2$O${}_4$$
• DFT+DMFT study of spin-charge-lattice coupling in covalent LaCoO${}_3$
• Acoustic study for dynamical molecular-spin state without undergoing magnetic phase transition in spin-frustrated ZnFe${}_2$O${}_4$
• Symmetry Preservation and Critical Fluctuations in a Pseudospin Crossover Perovskite LaCoO${}_3$
• Ga${}^{3+}$-substitution effects in the weak ferromagnetic oxide LaCo${}_{0.8}$Rh${}_{0.2}$O${}_3$
• Multiple lattice instabilities resolved by magnetic-field and disorder sensitivities in cubic paramagnetic phase of the orbital-degenerate frustrated spinel MgV${}_2$O${}_4$
• Damping of spinful excitons in LaCoO${}_3$ by thermal fluctuations: Theory and experiment
• Spin-state responses to light impurity doping in low-spin perovskite LaCoO${}_3$
• A variety of elastic anomalies in orbital-active nearly-itinerant cobalt vanadate spinel
• Orbital- and spin-driven lattice instabilities in quasi-one-dimensional CaV${}_2$O${}_4$
• Softening of breathing elastic mode and trigonal elastic mode in disordered pyrochlore magnet NaCaCo${}_2$F${}_7$

Cited by in corpus (1)

• Elastic softness of low-symmetry frustrated $A$Ti${}_2$O${}_5$ ($A$ = Co, Fe)