Dec 7 – 8, 2021 Online only
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Hidden Charge Order in an Iron Oxide Square-Lattice Compound

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Dec 7, 2021, 4:15 PM
Talk Structure Research Structure Research


Darren Peets (Technische Universität Dresden)


Since the discovery of charge disproportionation in the FeO$_2$ square-lattice compound Sr$_3$Fe$_2$O$_7$ by Mössbauer spectroscopy more than fifty years ago, the spatial ordering pattern of the disproportionated charges has remained “hidden” to conventional diffraction probes, despite numerous x-ray and neutron scattering studies. We have used neutron Larmor diffraction and Fe $K$-edge resonant x-ray scattering to demonstrate checkerboard charge order in the FeO$_2$ planes that vanishes at a sharp second-order phase transition upon heating above 332 K. Stacking disorder of the checkerboard pattern due to frustrated interlayer interactions broadens the corresponding superstructure reflections and greatly reduces their amplitude, thus explaining the difficulty of detecting them by conventional probes. We discuss the implications of these findings for research on “hidden order” in other materials.

Primary author

Darren Peets (Technische Universität Dresden)


Dr Jung-Hwa Kim (Max-Planck-Institut für Festkörperforschung) Dr Manfred Reehuis (HMI Berlin) Dr Peter Adler (MPI-CPfS) Dr Andrey Maljuk (IFW-Dresden) Dr Tobias Ritschel (Technische Universität Dresden) Dr Morgan Allison (Technische Universität Dresden) Prof. Jochen Geck (Technische Universität Dresden) Dr Jose Mardegan (PETRA-III, DESY) Dr Pablo Bereciartua Perez (PETRA-III, DESY) Dr Sonia Francoual (PETRA-III, DESY) Dr Andrew Walters (Max-Planck-Institut für Festkörperforschung) Thomas Keller (MPI for Solid State Research, Stuttgart) Dr Paula Abdala (ESRF) Dr Philip Pattison (ESRF) Mr Pinder Dosanjh (University of British Columbia) Prof. Bernhard Keimer (Max-Planck-Institut für Festkörperforschung)

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