Local structure study of the orbital order/disorder transition in LaMnO${}_3$

Abstract

We use a combination of neutron and X-ray total scattering measurements together with pair distribution function (PDF) analysis to characterise the variation in local structure across the orbital order--disorder transition in LaMnO${}_3$. Our experimental data are inconsistent with a conventional order--disorder description of the transition, and reflect instead the existence of a discontinuous change in local structure between ordered and disordered states. Within the orbital-ordered regime, the neutron and X-ray PDFs are best described by a local structure model with the same local orbital arrangements as those observed in the average (long-range) crystal structure. We show that a variety of meaningfully-different local orbital arrangement models can give fits of comparable quality to the experimental PDFs collected within the disordered regime; nevertheless, our data show a subtle but consistent preference for the anisotropic Potts model proposed in \emph{Phys Rev.\ B} {\bf 79}, 174106 (2009). The key implications of this model are electronic and magnetic isotropy together with the loss of local inversion symmetry at the Mn site. We conclude with a critical assessment of the interpretation of PDF measurements when characterising local symmetry breaking in functional materials.

arXiv comment14 pages, 8 figures, 3 tables

References in corpus (16)

• Dynamic Jahn-Teller Effect and Colossal Magnetoresistance in $L{a}_{1-x}{A}_{x}Mn{O}_3$
• Charge Ordering and Polaron Formation in the Magnetoresistive Oxide La0.7Ca0.3MnO3
• Spin Dynamics and Orbital State in LaTiO_3
• Orbital correlations in the pseudo-cubic \emph{O} and rhombohedral $R$-phases of LaMnO${}_3$
• Emergence of long-range order in BaTiO3 from local symmetry-breaking distortions
• Structure determination of disordered materials from diffraction data
• Orbital order induced metal-insulator transition in (La,Ca)MnO3
• Frustration driven lattice distortion; an NMR investigation of Y2Mo2O7
• Understanding the insulating phase in CMR manganites: Shortening of the Jahn-Teller long-bond across the phase diagram of La_{1-x} Ca_x Mn O_3
• Design of crystal-like aperiodic solids with selective disorder--phonon coupling
• Analysis of occupational and displacive disorder using the atomic pair distribution function: a systematic investigation
• Real space investigation of structural changes at the metal-insulator transition in VO2
• Orbital Dimer Model for Spin-Glass State in Y${}_2$Mo${}_2$O${}_7$
• Melting of the orbital order in LaMnO3 probed by NMR
• Local atomic and electronic structure in LaMnO_3 across the orbital ordering transition
• A Potts model for the distortion transition in LaMnO${}_3$

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• Bond Ordering and Molecular Spin-Orbital Fluctuations in the Cluster Mott Insulator GaTa${}_4$Se${}_8$
• Resolving Length Scale Dependent Transient Disorder Through an Ultrafast Phase Transition
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