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Title: The Checkerboard Pattern of the Charge-Ordered Phases in Bi1-xSrxMnO3 (x{<=}0.5) Studied by Resonant X-Ray Scattering at the Mn K Edge

Abstract

We report here resonant x-ray scattering (RXS) experiments carried out at the Mn K edge in Bi1-xSrxMnO3 (x=0.3, 0.5) single-crystals at room temperature. These compounds show a so-called charge ordered (CO) state at room temperature. Strong resonances were observed as the photon energy is tuned through the Mn K-edge for several weak superstructure (h 0 0) and (0 k 0) and forbidden (h/2 0 0) and (0 k/2 0) reflections with h, k odd within the a-b plane (Ibmm setting) in the x=0.3 and x=0.5 compounds, respectively. The reported azimuth angle and polarization dependences of the resonant intensity for the complete set of reflections point out to a structural transition at TCO that stabilizes a checkerboard ordering of two non-equivalent Mn atoms with different local geometrical structures. We conclude that the checkerboard ordered phase is a common ground state in the so-called CO manganites, A1-xBxMnO3, independently of the nature of the A and B atoms and for compositions x even far from 0.5. Moreover, the quantitative analysis of the resonant reflections shows that the electronic states of the two non-equivalent Mn atoms are far from the ionic (+3 and +4) species.

Authors:
; ;  [1]; ;  [2];  [3]
  1. Instituto de Ciencia de Materiales de Aragon ICMA, CSIC-Universidad de Zaragoza, C Pedro Cerbuna 12, 50009-Zaragoza (Spain)
  2. Institut de Ciencia de Materials de Barcelona, CSIC, Campus Universitari de Bellaterra, E-08193 Bellaterra (Spain)
  3. Institute of Chemical Technology, Technicka 5, 16628 Prague 6 (Czech Republic)
Publication Date:
OSTI Identifier:
21054628
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644525; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ATOMS; BISMUTH COMPOUNDS; CARBON MONOXIDE; CONCENTRATION RATIO; CRYSTAL STRUCTURE; ELECTRONIC STRUCTURE; GROUND STATES; MANGANATES; MONOCRYSTALS; PHOTONS; POLARIZATION; REFLECTION; RESONANCE; RESONANCE SCATTERING; STRONTIUM COMPOUNDS; X-RAY DIFFRACTION

Citation Formats

Subias, G., Garcia, J., Sanchez, M. C., Beran, P., Garcia-Munoz, J. L., and Nevriva, M.. The Checkerboard Pattern of the Charge-Ordered Phases in Bi1-xSrxMnO3 (x{<=}0.5) Studied by Resonant X-Ray Scattering at the Mn K Edge. United States: N. p., 2007. Web. doi:10.1063/1.2644525.
Subias, G., Garcia, J., Sanchez, M. C., Beran, P., Garcia-Munoz, J. L., & Nevriva, M.. The Checkerboard Pattern of the Charge-Ordered Phases in Bi1-xSrxMnO3 (x{<=}0.5) Studied by Resonant X-Ray Scattering at the Mn K Edge. United States. doi:10.1063/1.2644525.
Subias, G., Garcia, J., Sanchez, M. C., Beran, P., Garcia-Munoz, J. L., and Nevriva, M.. Fri . "The Checkerboard Pattern of the Charge-Ordered Phases in Bi1-xSrxMnO3 (x{<=}0.5) Studied by Resonant X-Ray Scattering at the Mn K Edge". United States. doi:10.1063/1.2644525.
@article{osti_21054628,
title = {The Checkerboard Pattern of the Charge-Ordered Phases in Bi1-xSrxMnO3 (x{<=}0.5) Studied by Resonant X-Ray Scattering at the Mn K Edge},
author = {Subias, G. and Garcia, J. and Sanchez, M. C. and Beran, P. and Garcia-Munoz, J. L. and Nevriva, M.},
abstractNote = {We report here resonant x-ray scattering (RXS) experiments carried out at the Mn K edge in Bi1-xSrxMnO3 (x=0.3, 0.5) single-crystals at room temperature. These compounds show a so-called charge ordered (CO) state at room temperature. Strong resonances were observed as the photon energy is tuned through the Mn K-edge for several weak superstructure (h 0 0) and (0 k 0) and forbidden (h/2 0 0) and (0 k/2 0) reflections with h, k odd within the a-b plane (Ibmm setting) in the x=0.3 and x=0.5 compounds, respectively. The reported azimuth angle and polarization dependences of the resonant intensity for the complete set of reflections point out to a structural transition at TCO that stabilizes a checkerboard ordering of two non-equivalent Mn atoms with different local geometrical structures. We conclude that the checkerboard ordered phase is a common ground state in the so-called CO manganites, A1-xBxMnO3, independently of the nature of the A and B atoms and for compositions x even far from 0.5. Moreover, the quantitative analysis of the resonant reflections shows that the electronic states of the two non-equivalent Mn atoms are far from the ionic (+3 and +4) species.},
doi = {10.1063/1.2644525},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • Resonant x-ray scattering (RXS) at the Mn K edge has been used to characterize the low temperature ordered phase of Bi{sub 0.5}Sr{sub 0.5}MnO{sub 3}. Strong resonances were observed for the (030), (050), (05/20), (0 7/2 0), (4 (1/2) 0), and (3 (1/2) 0) reflections as the photon energy is tuned through the Mn K edge. The reported azimuthal and polarization dependence of the resonant intensities indicates that the low temperature phase is described as a checkerboard ordering of two types of Mn sites with different local geometrical structures. One of the sites is anisotropic, a tetragonal distorted oxygen octahedron andmore » the other one is isotropic, a nearly undistorted oxygen octahedron. The distinction of these two Mn sites is accompanied by a displacement of the Mn atoms transverse to the b axis. We conclude that this checkerboard-ordered pattern is a common ground state in half-doped manganites. Intermediate valence states according to fractional charge segregation were deduced for the two nonequivalent Mn atoms, far from the localized Mn{sup 3+} and Mn{sup 4+} ionic species. Hence, the experimental data discard the ionic model of charge and orbital ordering of localized 3d (or 3d-like) states at the Mn site (or the MnO{sub 6} cluster). We suggest a description of the RXS in terms of band structure effects and lattice dynamics.« less
  • The charge and spin correlations in La 1.875 Ba 0.125 CuO 4 (LBCO 1/8) are studied using Cu L 3 edge resonant inelastic x-ray scattering (RIXS). The static charge order (CO) is observed at a wave vector of ( 0.24 , 0 ) and its charge nature confirmed by measuring the dependence of this peak on the incident x-ray polarization. The damped spin excitation or “paramagnon” in LBCO 1/8 is then measured as it disperses through the CO wave vector. Within the experimental uncertainty no changes are observed in the paramagnon at that wave vector and the paramagnon seems tomore » be similar to that measured in other cuprates, which have no static CO. Given that the stripe correlation modulates both the charge and spin degrees of freedom, it is likely that subtle changes do occur in the paramagnon due to CO. Consequently, we propose that future RIXS measurements, realized with higher-energy resolution and sensitivity, should be performed to test for these effects.« less
  • We use hard x-ray resonant inelastic x-ray scattering (RIXS) and density functional theory (DFT) calculations to characterize charge transfer excitations in K{sub 3}Mn(CN){sub 6}. The combination of RIXS measurements and DFT calculations allows us to characterize the strength of the ligand-metal electronic interaction and assign the Raman resonances in the RIXS spectra to charge transfer excitations. With x-ray excitation energies resonant with the T{sub 2g} and E{sub g} pre-edge peaks derived predominantly from the Mn 3d orbitals, we observe Raman resonances in the energy transfer range from 2 to 12 eV, which results from the filling of the 1s core-holemore » from T{sub 1u}-symmetry occupied orbitals. DFT calculations indicate that these orbitals exhibit primarily ligand character, supporting the assignment of the energy transfer resonances to ligand-to-metal charge transfer excitations. Our RIXS measurements and DFT calculations also indicate that the E{sub g}-orbital spin-splits by roughly 0.8 eV, though we do not cleanly resolve the two absorption peaks in the RIXS spectra. We also see evidence for a metal-to-ligand charge transfer (MLCT) excitation when exciting with a 6545.0 eV incident photon, roughly 4 eV above the E{sub g} absorption peaks. The 6545.0 eV resonant emission spectrum shows a 6.0 eV energy transfer resonance, which corresponds to a final state hole in the T{sub 2g} partially occupied orbital. DFT calculations indicate that excitation at 6545.0 eV populates an unoccupied T{sub 1u}-symmetry orbital of primarily ligand character. Given the predominantly metal character of the final state hole, we assign the 6.0 eV Raman resonance to a MLCT excitation. These measurements demonstrate the ability of hard x-ray RIXS to characterize the valence electronic structure of coordination compounds.« less
  • The charge ordered state in Yb4As3 has been studied by a resonant x-ray scattering (RXS) technique near the Yb L3-edge. The anomalous scattering factors, f' and f'', of Yb3+ and Yb2+ have been determined using the absorption spectrum of the Yb4As3. Based on the anomalous scattering factors, the valences of the two inequivalent Yb sites, +2 25 -{delta} and +2 25 + 3{delta}, have been evaluated by the RXS intensity corresponding to the charge ordering. The fully charge ordered state of {delta} = 0 25 {+-} 0 02 was elucidated.