X-ray-absorption near-edge spectroscopy and circular magnetic x-ray dichroism at the Mn<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>edge of magnetoresistive manganites

Subı́as, G.; García, J.; Proietti, M. G.; Blasco, J.

doi:10.1103/physrevb.56.8183

Cited by 189 publications

(189 citation statements)

References 44 publications

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“…This result is in contrast with the belief at the early stage of the research of the CO-OO phenomena, but in accord with the recent results 16,17,18,19,20,21,22,23,24,25 . This indicates that various interactions, such as electron-lattice, Coulomb repulsion, and magnetic interactions, should be taken into account to correctly understand the nature of chargeordered state.…”

Section: Discussioncontrasting

confidence: 57%

“…Many diffraction and theoretical studies have reported the checkerboard type charge order of Mn 3+ and Mn 4+ ions with charge disproportionation and stripe-type orbital order, explaining a complex antiferromagnetic spin order at low temperatures in half-doped manganites 7,8,9,10,11,12,13,14,15,16 . On the other hand, another model with less distinct charge disproportionation has also been proposed 17,18,19,20,21,22,23,24,25 . For example, taking into account the on-site Coulomb interaction, Brink et al have suggested 17 that maximum value of charge disproportionation is as little as 20%.…”

Section: Introductionmentioning

confidence: 99%

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Lattice-form-dependent orbital shape and charge disproportionation in charge- and orbital-ordered manganites

et al. 2009

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The orbital shapes and charge disproportionations at nominal Mn 3+ and Mn 4+ sites for the chargeand orbital-ordered phases have been studied on half-doped manganites Pr(Sr0.1Ca0.9)2Mn2O7 and Eu0.5Ca1.5MnO4 with double-layer and single-layer Mn-O networks, respectively, by means of xray structural analyses, in comparison with Pr0.5Ca0.5MnO3 with the pseudo cubic network. In a single-layer Eu0.5Ca1.5MnO4 system, the (y 2 −z 2 )/(z 2 −x 2 )-type orbital shape is observed, while the (3y 2 −r 2 )/(3x 2 −r 2 )-type orbital shape in a pseudo cubic Pr0.5Ca0.5MnO3 system. In a double-layer Pr(Sr0.1Ca0.9)2Mn2O7 system, the orbital shape is found to undergo a large change upon thermally induced rotation of orbital stripe. Furthermore, clear charge disproportionation is observed for the pseudo cubic and double-layer systems, while not in the single-layer system. These results indicate that the orbital shape and charge disproportionation are sensitive to the dimension of Mn-O network.

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Section: Discussioncontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Lattice-form-dependent orbital shape and charge disproportionation in charge- and orbital-ordered manganites

et al. 2009

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“…We performed X-ray absorption fine structure (XAFS) measurements at the Mn K-edge to probe its valence change. The K-edge threshold energy continuously increases with increasing Mn valence 25 . Details of the XAFS analysis are given in the Methods section and Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In ref. 47, E 0 of Mn 3 þ in LaMnO 3 is 6,450.6 eV and E 0 of Mn 4 þ in CaMnO 3 is 6,454.8 eV. E 0 of the superlattices and the LaMnO 3 þ d thin film is marked in the inset of Supplementary Fig.…”

Section: Discussionmentioning

confidence: 99%

Correlating interfacial octahedral rotations with magnetism in (LaMnO3+δ)N/(SrTiO3)N superlattices

et al. 2014

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Lattice distortion due to oxygen octahedral rotations have a significant role in mediating the magnetism in oxides, and recently attracts a lot of interests in the study of complex oxides interface. However, the direct experimental evidence for the interrelation between octahedral rotation and magnetism at interface is scarce. Here we demonstrate that interfacial octahedral rotation are closely linked to the strongly modified ferromagnetism in (LaMnO 3 þ d ) N / (SrTiO 3 ) N superlattices. The maximized ferromagnetic moment in the N ¼ 6 superlattice is accompanied by a metastable structure (space group Imcm) featuring minimal octahedral rotations (a À a À c À , aB4.2°, gB0.5°). Quenched ferromagnetism for No4 superlattices is correlated to a substantially enhanced c axis octahedral rotation (a À a À c À , aB3.8°, gB8°f or N ¼ 2). Monte-Carlo simulation based on double-exchange model qualitatively reproduces the experimental observation, confirming the correlation between octahedral rotation and magnetism. Our study demonstrates that engineering superlattices with controllable interfacial structures can be a feasible new route in realizing functional magnetic materials.

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“…The main absorption edge in the XANES spectrum shifts to higher energy with increasing oxidation state (chemical shift) [41]. Because of this chemical shift of some few electron volts between different ionic states, Mn K-edge and Fe K-edge XANES have been successfully used to demonstrate the absence of a bimodal distribution of either Mn 3+ and Mn 4+ ions in manganites [42] or Fe 3+ and Fe 5+ ions in the La 1−x Sr x FeO 3 series [43], respectively. Moreover, the extended part of the XAS spectra [i.e.…”

Section: Introductionmentioning

confidence: 99%

Strong local lattice instability in hexagonal ferritesRFe2O4(R= Lu,Y,Yb) revealed by x-ray absorption spe

et al. 2014

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We present here an x-ray absorption study of the RFe 2 O 4 series (LuFe 2 O 4 , YFe 2 O 4 , YbFe 2 O 4 , and LuCoFeO 4 ) at the Fe K-edge. Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectra were measured at temperatures ranging from 100 K to 390 K crossing the charge ordering (CO) transition temperatures on both isotropic and oriented powder samples. Unpolarized and polarized x-ray absorption spectra with the x-ray polarization parallel and perpendicular to the hexagonal c axis were obtained separately. The XANES spectra show almost no dependence with either polarization or temperature. This indicates that, in contrast to its average crystallographic structure, the local electronic and geometrical state of the Fe atom is barely anisotropic, and it remains the same above and below the proposed CO. Moreover, the linear combination of two spectra corresponding to the pure ionic states Fe 2+ and Fe 3+ does not fit to the experimental XANES of either LuFe 2 O 4 , YFe 2 O 4 , or YbFe 2 O 4 , discarding total ionic segregation in favor of an intermediate mixed valence state. The maximum charge disproportionation compatible with the XANES spectra is 0.5 ± 0.1 electrons in the whole temperature range. The polarized EXAFS spectra have allowed us to analyze the local structure separating the different contributions mixed up in the polycrystal. Best-fit results show that the five oxygen atoms of the first coordination shell are at nearly the same distance but with a large Debye-Waller factor. Neither the interatomic distances nor the Debye-Waller factors of the first oxygen coordination shell change with temperature, indicating that the dynamical structural distortion of the high-temperature symmetric hexagonal phase freezes upon cooling down. Thus, the local structure instability of the mixed valence is in the origin of the structural transitions.

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X-ray-absorption near-edge spectroscopy and circular magnetic x-ray dichroism at the MnKedge of magnetoresistive manganites

Cited by 189 publications

References 44 publications

Lattice-form-dependent orbital shape and charge disproportionation in charge- and orbital-ordered manganites

Lattice-form-dependent orbital shape and charge disproportionation in charge- and orbital-ordered manganites

Correlating interfacial octahedral rotations with magnetism in (LaMnO3+δ)N/(SrTiO3)N superlattices

Strong local lattice instability in hexagonal ferritesRFe2O4(R= Lu,Y,Yb) revealed by x-ray absorption spe

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