Symmetry and charge order in Fe2OBO3 studied through polarized resonant x-ray diffraction

Bland, S.R.; Adiga, S.; Johnson, R.D.; Angst, M.; Hatton, P.D.; Scagnoli, V.; Herrero-Martin, J.

doi:10.1103/PhysRevB.82.115110

Journal Article

Symmetry and charge order in Fe2OBO3 studied through polarized resonant x-ray diffraction

Bland, S. R. ; Angst, M.FZJ* ; Adiga, S.FZJ* ; Scagnoli, V. ; Johnson, R. D. ; Herrero-Martin, J. ; Hatton, P. D.

2010
APS College Park, Md.

Physical review / B 82(11), 115110 (2010) [10.1103/PhysRevB.82.115110]

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Please use a persistent id in citations: http://hdl.handle.net/2128/10971 doi:10.1103/PhysRevB.82.115110

Abstract: Bond valence sum calculations have previously suggested that iron oxyborate exhibits charge order of the Fe ions with integer 2+/3+ valence states. Meanwhile transition metal oxides typically show much smaller, fractional charge disproportionations. Using resonant x-ray diffraction at the iron K edge, we find resonant features which are much larger than those ordinarily observed in charge ordered oxides. Simulations were subsequently performed using a cluster-based, monoelectronic code. The nanoscale domain structure prevents precise fitting; nevertheless the simulations confirm the diagonal charge order symmetry, as well as the unusually large charge disproportionation. We have demonstrated the conversion of linearly to nonlinearly polarized light and vice versa through full polarization analysis. Simulations show that this effect principally results from interference between the isotropic and anisotropic scattering terms. This mechanism is likely to account for similar observations in alternative systems.

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Physics, Condensed Matter

Note: The authors wish to thank the ESRF for the beamtime and experimental support. S.R.B., R.D.J., and P.D.H. thank EPSRC and STFC for funding. M.A. and S.A. acknowledge support by the Initiative and Networking Fund of the Helmholtz Association of German Research Centers through the Helmholtz-University Young Investigator Group Complex Ordering Phenomena in Multifunctional Oxides and by the institute of scattering methods. S.R.B. thanks Y. Joly for helpful discussions and assistance with FDMNES, and C. B. Buckley for additional experimental support. The authors thank R. P. Hermann for preliminary measurements and helpful EXAFS discussions and results. This work was partially performed on the EPSRC-funded XMaS beamline at the ESRF, directed by M. J. Cooper and C. A. Lucas. We are grateful to the beamline team of S. D. Brown, P. Normile, O. Bikondoa, L. Bouchenoire, and P. Thompson for their invaluable assistance, and to S. Beaufoy and J. Kervin for additional support.

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Appears in the scientific report 2010

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