The Microscopic Nature of Orbital Disorder in LaMnO$_{3}$

Fuente: arXiv
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Main Authors: Batnaran, Bodoo, Goodwin, Andrew L., Hayward, Michael A., Deringer, Volker L.
Format: Preprint
Published: 2025
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author Batnaran, Bodoo
Goodwin, Andrew L.
Hayward, Michael A.
Deringer, Volker L.
author_facet Batnaran, Bodoo
Goodwin, Andrew L.
Hayward, Michael A.
Deringer, Volker L.
contents We present a revised atomistic picture of the order-disorder transition in the archetypal orbital-ordered perovskite material, LaMnO$_{3}$. Our study uses machine-learning-driven molecular-dynamics simulations which describe the temperature evolution of pair distribution functions in close agreement with experiment. We find the orbital-disordered phase in LaMnO$_{3}$ to comprise a mixture of differing structural distortions with and without inversion symmetry, implying a mixture of different orbital arrangements. These distortions are highly dynamic with an estimated lifetime of $\sim 40$ fs at 1,000 K, and their fluctuations converge with the timescales of conventional thermal motion in the high-$T$ phase - indicating that the electronic instability responsible for static Jahn-Teller distortions at low temperature instead drives phonon anharmonicity at high temperatures. Beyond LaMnO$_{3}$, our work opens an avenue for studying a wider range of correlated materials.
format Preprint
id arxiv_https___arxiv_org_abs_2510_25414
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Microscopic Nature of Orbital Disorder in LaMnO$_{3}$
Batnaran, Bodoo
Goodwin, Andrew L.
Hayward, Michael A.
Deringer, Volker L.
Materials Science
Chemical Physics
We present a revised atomistic picture of the order-disorder transition in the archetypal orbital-ordered perovskite material, LaMnO$_{3}$. Our study uses machine-learning-driven molecular-dynamics simulations which describe the temperature evolution of pair distribution functions in close agreement with experiment. We find the orbital-disordered phase in LaMnO$_{3}$ to comprise a mixture of differing structural distortions with and without inversion symmetry, implying a mixture of different orbital arrangements. These distortions are highly dynamic with an estimated lifetime of $\sim 40$ fs at 1,000 K, and their fluctuations converge with the timescales of conventional thermal motion in the high-$T$ phase - indicating that the electronic instability responsible for static Jahn-Teller distortions at low temperature instead drives phonon anharmonicity at high temperatures. Beyond LaMnO$_{3}$, our work opens an avenue for studying a wider range of correlated materials.
title The Microscopic Nature of Orbital Disorder in LaMnO$_{3}$
topic Materials Science
Chemical Physics
url https://arxiv.org/abs/2510.25414