Observation of orbital ordering and Jahn-Teller distortions supporting the Wigner-crystal model in highly doped<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Bi</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">Ca</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi mathvariant="normal">Mn</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</m

Grenier, Stéphane; Kiryukhin, V.; Cheong, Sang‐Wook; Kim, B.G.; Hill, J. P.; Thomas, K. J.; Tonnerre, J. M.; Joly, Yves; Staub, U.; Scagnoli, V.

doi:10.1103/physrevb.75.085101

Cited by 19 publications

(19 citation statements)

References 30 publications

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“…Numerous electron, x-ray and neutron diffraction experiments studied the stripe phases in various overdoped manganites, however, without reaching a clear conclusion [176, 177, 187-189, 192, 193, 201, 202]. Concerning the question about bi-stripe versus Wigner model, the larger part of the experiments favor the Wigner model [187,198,199,203] for the perovskites compounds, whereas experiments on double-layer manganites were interpreted in terms of the bi-stripe model [192,193] but a clear experimental proof for one of the two scenarios is still missing. Note, however, that only for doping above x = 0.6 there is a difference between the two models as otherwise bi-stripes form also in the Wigner model.…”

Section: Incommensurate Order Of Charges Spins and Orbitals In Layermentioning

confidence: 99%

Neutron scattering studies on stripe phases in non-cuprate materials

Ulbrich

Braden

2012

Physica C: Superconductivity

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Several non-cuprates layered transition-metal oxides exhibit clear evidence for stripe ordering of charges and magnetic moments. Therefore, stripe order should be considered as the typical consequence of doping a Mott insulator, but only in cuprates stripe order or fluctuating stripes coexist with metallic properties. A linear relationship between the charge concentration and the incommensurate structural and magnetic modulations can be considered as the finger print of stripe ordering with localized degrees of freedom. In nickelates and in cobaltates with K 2 NiF 4 structure, doping suppresses the nearest-neighbor antiferromagnetism and induces stripe order. The higher amount of doping needed to induce stripe phases in these non-cuprates series can be attributed to reduced charge mobility. Also manganites exhibit clear evidence for stripe phases with further enhanced complexity, because orbital degrees of freedom are involved. Orbital ordering is the key element of stripe order in manganites since it is associated with the strongest structural distortion and with the perfectly fulfilled relation between doping and incommensurability. Magnetic excitations in insulating stripe phases exhibit strong similarity with those in the cuprates, but only for sufficiently short magnetic correlation lengths reflecting well-defined magnetic stripes that are only loosely coupled.

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Section: Incommensurate Order Of Charges Spins and Orbitals In Layermentioning

confidence: 99%

Neutron scattering studies on stripe phases in non-cuprate materials

Ulbrich

Braden

2012

Physica C: Superconductivity

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“…We observed equal spectra for the two incident polarizations. As has been discussed elsewhere [10] this implies that the scattering process is one in which the polarization of the photon is rotated, of the type σ → π or π → σ, that is, with zero σ → σ and π → π scattering. The incommensurability of this reflection is observed to vary with temperature, stabilizing at about 0.31 r.l.u., below T OO (Fig.…”

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confidence: 99%

“…The first observation indicates a resonant superstructure reflection from an ordering of the very first unoccupied states from ε f projected on the O atoms (ψ O 1s ), with the propagation Q = 0.31 r.l.u, corresponding to the periodicity of the Mn orbital ordering [10]. Following earlier analysis of the absorption data [14], the comparison with the fluorescence yield allows us to identify the ordered states as the 2p states hybridized with the 3d.…”

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confidence: 99%

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Direct Observation of Oxygen Superstructures in Manganites

et al. 2007

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We report the observation of superstructures associated with the oxygen 2p-states in two prototypical manganites using x-ray diffraction at the oxygen K-edge. We determine the nature of the orderings and discuss our picture with respect to novel theoretical models. In the stripe order system Bi0.31Ca0.69MnO3, hole-doped O states are found to be orbitally ordered, at the same propagation vector as the Mn orbital ordering, but no evidence is found to support a picture of oxygen charge stripes at this periodicity. In La 7 8 Sr 1 8 MnO3, we observe a 2p charge ordering described by alternating hole-poor and hole-rich MnO planes that is consistent with recent predictions.Fascinating macroscopic properties may emerge from the electronic and magnetic orderings that occur in 3d metal oxides doped with charge carriers. In doped cuprates, charge and spin stripes could be relevant to high-T C superconductivity [1], and the colossal magnetoresistance of doped manganites is fundamentally related to the stability, in a magnetic field, of an ordering of polarons together with an ordering of charge, orbital and magnetic moments on the Mn atoms [2]. The relationship between the orderings and the transport properties has been adressed both theoretically and experimentally concentrating on the 3d metal atoms, often neglecting the ligands' degrees of freedom. However, because the active states are not ionic 3d metal orbitals, but, rather hybridized metal 3d -oxygen 2p states, an ordering of the oxygens may be related to the ordering of the metals. In cuprates, the role of the oxygen atom is now always considered and, taking a recent example, the ordering of hole-doped oxygens was directly observed and discussed in the context of the stripes [3].In manganites, an electronic ordering on oxygens has not been detected yet although recent experiments suggested a crucial role of the O atoms in the polaronic, electronic, and magnetic orderings of the Mn atoms. A relation between conductivity and the O electronic configuration was identified [4]; spectroscopic studies indicated a small charge disproportionation on Mn atoms instead of an ionic charge ordering (Mn 4+ /Mn 3+ ) [5], and a crystallographic study proposed that the oxygen atom bridges an electron between two Mn atoms of nearly the same valence, coupling them magnetically [6]. At the heart of these results is the explicit role of the 2p − 3d hybridization in determining the magnetic exchange couplings and conductivity, the traditional picture being the one where the atomic 3d orbitals define exchange magnetic pathways between Mn atoms, the oxygen 2p states being filled.Meanwhile, new theoretical models beyond the Mncentered description also suggested that oxygen superstructures play an important role in determining the ground states. Ferrari et al. [7] explained the insulating behavior of the charge/orbitally orded half-doped system by an ordering of O holes -"oxygen stripes" of varying valences (incidentally, having the same periodicity as the Mn orbital ordering). Efremov et al...

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“…The result [10] is the first proposal for the long sought low temperature structure of Fe 3 O 4 . This technique has also been used to contradict an unconventional model of charge ordering in half-doped manganites, confirming the checker board pattern at half doping by Grenier et al [11], and to suggest pattern in large unit cells resulting from a large charge ordering propagation vector [12] (see Herrero-Martin et al review). REXS is capable of distinguishing space groups and indicating neighbour atoms' displacements around the resonant atoms, providing a great help in cases where conventional crystallographic techniques are hard pressed to determine even symmetry elements in the charge-ordered unit cell.…”

Section: Motivationmentioning

confidence: 65%