Volume collapse in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>LaMnO</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>studied using an anisotropic Potts model

Ahmed, Mahrous R.; Gehring, G A

doi:10.1103/physrevb.79.174106

Cited by 13 publications

(22 citation statements)

References 28 publications

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“…We cautiously identify a subtle but persistent preference for the anisotropic Potts model proposed in Ref. 31. This assignment is consistent with the discontinuous change in local structure at T JT evident in our newly-obtained data.…”

Section: Introductionsupporting

confidence: 89%

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Local structure study of the orbital order/disorder transition inLaMnO3

et al. 2017

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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 LaMnO3. 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 Phys Rev. B 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.

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Section: Introductionsupporting

confidence: 89%

“…31 and summarised here for completeness. The 3SP model is a statistical model in which each MnO 6 octahedron is free to adopt one of three possible states, corresponding to the three possible axes along which opposing pairs of long Mn-O bonds might orient.…”

Section: Orbital Correlations In the O Phasementioning

confidence: 99%

Local structure study of the orbital order/disorder transition inLaMnO3

et al. 2017

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“…Below T c2 a collective Jahn-Teller effect breaks the electronic symmetry by shifting the orbital character towards d xz,σ or d yz,σ while at the same time moving Q 2 away from the origin. A similar dynamical regime is present in LaMnO 3 but at much higher temperature (T JT = 700 K) due to strong electron-lattice coupling [13]. The static local Jahn-Teller effect usually leads to an anti-ferro distorted order, which globally preserves the tetragonal (C4) symmetry (see Fig.…”

Section: Discussion and Interpretationmentioning

confidence: 67%

“…Upon lowering the temperature below T c2 the a and b-axis parameters separate, and the c-axis shrinks. The volume remains unchanged at the transition at T c2 (1% of volume collapse was reported in LaMnO 3 at the Jahn-Teller transition [13,14,19]), but it slightly expands (0.02%) upon cooling below T c1 (Fig. 2a).…”

Section: X-ray Powder Diffraction Datamentioning

confidence: 78%

“…We also present theoretical arguments that the orbital ordering in Sr 2 VO 4 is accompanied by an intermediate orthorhombic distortion stabilized by electron-lattice interactions. Examples of lattice mediated orbital ordering are well known in KCuF 3 [12] or in LaMnO 3 [13,14]. However, in those compounds e g electrons are involved, therefore the spin-orbit coupling does not play an essential role, contrary to the situation in Sr 2 VO 4 .…”

Section: Introductionmentioning

confidence: 99%

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Jahn-Teller induced nematic orbital order in tetragonalSr2VO4

et al. 2016

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Using high resolution X-Ray diffraction (XRD) on high purity powders, we resolved the structure and ab symmetry of the intriguing compound Sr2VO4 from room temperature down to 20 K to an unprecedented level of accuracy. Upon cooling, this new set of data unambiguously reveals a second order phase transition lowering the symmetry from tetragonal to orthorhombic at a temperature Tc2 = 136 K. The observation of an orthorhombic distortion of the ab-plane is attributed to nematic phase formation supported by local Jahn-Teller (JT) dynamical instability. At TN = 105 K, spins order and at Tc1 = 100 K the tetragonal structure is recovered with an elongated c-axis.

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Displacive Jahn–Teller Transition in NaNiO₂

Nagle-Cocco,

Genreith-Schriever,

Steele

et al. 2024

J. Am. Chem. Soc.

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Below its Jahn−Teller transition temperature, T JT , NaNiO 2 has a monoclinic layered structure consisting of alternating layers of edge-sharing NaO 6 and Jahn−Teller-distorted NiO 6 octahedra. Above T JT where NaNiO 2 is rhombohedral, diffraction measurements show the absence of a cooperative Jahn−Teller distortion, accompanied by an increase in the unit cell volume. Using neutron total scattering, solid-state Nuclear Magnetic Resonance (NMR), and extended X-ray absorption fine structure (EXAFS) experiments as local probes of the structure we find direct evidence for a displacive, as opposed to order− disorder, Jahn−Teller transition at T JT . This is supported by ab initio molecular dynamics (AIMD) simulations. To our knowledge this study is the first to show a displacive Jahn−Teller transition in any material using direct observations with local probe techniques.

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Volume collapse inLaMnO3studied using an anisotropic Potts model

Cited by 13 publications

References 28 publications

Local structure study of the orbital order/disorder transition inLaMnO3

Local structure study of the orbital order/disorder transition inLaMnO3

Jahn-Teller induced nematic orbital order in tetragonalSr2VO4

Displacive Jahn–Teller Transition in NaNiO₂

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Volume collapse inLaMnO3studied using an anisotropic Potts model

Cited by 13 publications

References 28 publications

Local structure study of the orbital order/disorder transition inLaMnO3

Local structure study of the orbital order/disorder transition inLaMnO3

Jahn-Teller induced nematic orbital order in tetragonalSr2VO4

Displacive Jahn–Teller Transition in NaNiO2

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Displacive Jahn–Teller Transition in NaNiO₂