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The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite

Based on an integrated study of magnetic susceptibility, specific heat, and thermal expansion of single-crystal LaCoO(3) free from cobalt and oxygen vacancies, two narrow spin gaps are identified before and after the phonon softening of gap size ΔE ∼ 0.5 meV in a CoO(6)-octahedral crystal electric f...

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Autores principales: Shu, Guo-Jiun, Wu, Pei-Chieh, Chou, F. C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9058157/
https://www.ncbi.nlm.nih.gov/pubmed/35514908
http://dx.doi.org/10.1039/d0ra09675j
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author Shu, Guo-Jiun
Wu, Pei-Chieh
Chou, F. C.
author_facet Shu, Guo-Jiun
Wu, Pei-Chieh
Chou, F. C.
author_sort Shu, Guo-Jiun
collection PubMed
description Based on an integrated study of magnetic susceptibility, specific heat, and thermal expansion of single-crystal LaCoO(3) free from cobalt and oxygen vacancies, two narrow spin gaps are identified before and after the phonon softening of gap size ΔE ∼ 0.5 meV in a CoO(6)-octahedral crystal electric field (CEF) and the thermally activated spin gap Q ∼ 25 meV, respectively. Significant excitation of Co(3+) spins from a low-spin (LS) to a high-spin (HS) state is confirmed by the thermal activation behavior of spin susceptibility χ(S) of energy gap Q ∼ 25 meV, which follows a two-level Boltzmann distribution to saturate at a level of 50% LS/50% HS statistically above ∼200 K, without the inclusion of a postulated intermediate spin (IS) state. A threefold increase in the thermal expansion; coefficient (α) across the same temperature range as that of thermally activated HS population growth is identified, which implies the non-trivial spin–orbit–phonon coupling caused the bond length of Co(3+(LS↔HS))–O fluctuation and the local lattice distortion. The unusually narrow gap of ΔE ∼ 0.5 meV for the CoO(6) octahedral CEF between e(g)–t(2g) indicates a more isotropic negative charge distribution within the octahedral CEF environment, which is verified by the Electron Energy Loss Spectroscopy (EELS) study to show nontrivial La–O covalency.
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spelling pubmed-90581572022-05-04 The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite Shu, Guo-Jiun Wu, Pei-Chieh Chou, F. C. RSC Adv Chemistry Based on an integrated study of magnetic susceptibility, specific heat, and thermal expansion of single-crystal LaCoO(3) free from cobalt and oxygen vacancies, two narrow spin gaps are identified before and after the phonon softening of gap size ΔE ∼ 0.5 meV in a CoO(6)-octahedral crystal electric field (CEF) and the thermally activated spin gap Q ∼ 25 meV, respectively. Significant excitation of Co(3+) spins from a low-spin (LS) to a high-spin (HS) state is confirmed by the thermal activation behavior of spin susceptibility χ(S) of energy gap Q ∼ 25 meV, which follows a two-level Boltzmann distribution to saturate at a level of 50% LS/50% HS statistically above ∼200 K, without the inclusion of a postulated intermediate spin (IS) state. A threefold increase in the thermal expansion; coefficient (α) across the same temperature range as that of thermally activated HS population growth is identified, which implies the non-trivial spin–orbit–phonon coupling caused the bond length of Co(3+(LS↔HS))–O fluctuation and the local lattice distortion. The unusually narrow gap of ΔE ∼ 0.5 meV for the CoO(6) octahedral CEF between e(g)–t(2g) indicates a more isotropic negative charge distribution within the octahedral CEF environment, which is verified by the Electron Energy Loss Spectroscopy (EELS) study to show nontrivial La–O covalency. The Royal Society of Chemistry 2020-11-26 /pmc/articles/PMC9058157/ /pubmed/35514908 http://dx.doi.org/10.1039/d0ra09675j Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/
spellingShingle Chemistry
Shu, Guo-Jiun
Wu, Pei-Chieh
Chou, F. C.
The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite
title The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite
title_full The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite
title_fullStr The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite
title_full_unstemmed The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite
title_short The spin–orbit–phonon coupling and crystalline elasticity of LaCoO(3) perovskite
title_sort spin–orbit–phonon coupling and crystalline elasticity of lacoo(3) perovskite
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9058157/
https://www.ncbi.nlm.nih.gov/pubmed/35514908
http://dx.doi.org/10.1039/d0ra09675j
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