Journal Article

FZJ-2026-05519

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Phonons Reflect Dynamic Spin-State Order in LaCoO$_3$

Ivashko, A. (First author)Extern* ; Manjo, T. (Collaboration author)Extern* ; Kauth, M. (Collaboration author)Extern* ; Tymoshenko, Y. (Collaboration author)Extern* ; Merritt, A. M. (Collaboration author)Extern* ; Bohnen, K.-P. (Collaboration author)Extern* ; Heid, R. (Collaboration author)Extern* ; Merz, M. (Collaboration author)Extern* ; Eich, A. (Collaboration author)Extern*FZJ* ; Castellan, J.-P. (Collaboration author)Extern* ; Ivanov, A. (Collaboration author)Extern* ; Schreiber, N. (Collaboration author)Extern* ; Zheng, H. (Collaboration author)Extern* ; Mitchell, J. F. (Collaboration author)Extern* ; Meven, M. (Collaboration author)FZJ*RWTH* ; Park, J. T. (Collaboration author)MLZ* ; Ishikawa, D. (Collaboration author)Extern* ; Nakamura, Y. (Collaboration author)Extern* ; Baron, A. Q. R. (Collaboration author)Extern* ; Weber, F.Extern*

2026
APS College Park, Md.

Please use a persistent id in citations: doi:10.1103/tsw6-sdhk  doi:10.34734/FZJ-2026-05519

Abstract: We investigate lattice dynamics in LaCoO$_3$ using inelastic neutron and x-ray scattering over T=2 − 6⁢5⁢0  K, spanning the spin-state crossover at T$_1$ ≈ 1⁢0⁢0  K and the insulator-metal transition at T$_2$ ≈ 5⁢5⁢0  K. Comparison with quasiharmonic ab initio lattice-dynamical calculations helps reveal anomalous softening of a ≈ 1⁢0−meV oxygen phonon, confined to the temperature interval T$_1$ ≤ T ≤ T$_2$ and localized in momentum space at 𝐪$_{SSO}$ = (½,½,½)$_c$. This wave vector is characteristic of the spin-state-ordering pattern originally proposed by Goodenough [An interpretation of the magnetic properties of the perovskite-type mixed crystals La$_{1−x}$⁢Sr$_x$⁢CoO$_{3−𝜆}$, J. Phys. Chem. Solids 6, 287 (1958)]. Our results provide momentum-resolved evidence for dynamic correlations of high-spin and low-spin Co$^{3+}$ states characterized by 𝐪$_{SSO}$=(½,½,½)$_c$, demonstrating that phonons are sensitive probes of fluctuating spin-state correlations in LaCoO$_3$.

Keyword(s): Magnetic Materials (1st) ; Condensed Matter Physics (2nd) ; Crystallography (2nd) ; Magnetism (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS-FRM-II)
2. JCNS-4 (JCNS-4)
3. JARA-FIT (JARA-FIT)
4. Heinz Maier-Leibnitz Zentrum (MLZ)

Research Program(s):

1. 6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ) (POF4-6G4) (POF4-6G4)
2. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
3. DFG project G:(GEPRIS)460248799 - DAPHNE4NFDI - DAten aus PHoton- und Neutronen Experimenten für NFDI (DAPHNE4NFDI) (460248799) (460248799)
4. 05K22VK1 - Parabolische geschachtelte Spiegeloptik für thermische Neutronen am Dreiachsenspektrometer PUMA (BMBF-05K22VK1) (BMBF-05K22VK1)

Experiment(s):

1. HEiDi: Single crystal diffractometer on hot source (SR9b)
2. Measurement at external facility

Appears in the scientific report 2026

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Electronics and Telecommunications Collection ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 5 ; JCR ; Nationallizenz ; SCOAP3 sponsored Journal ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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