Direct probe of oxygen superstructures in manganites

Stéphane Grenier (1) , K. J. Thomas (2) , J.P. Hill (2) , U. Staub (3) , Y. Bodenthin (3) , M. Garcia-Fernandez (3) , V. Scagnoli (4) , V. Kiryukhin (5) , S.-W. Cheong (5) , B. G. Kim (5) , Jean-Marc Tonnerre (1)

1 NEEL - SIN - Surfaces, Interfaces et Nanostructures
2 BNL - Brookhaven National Laboratory [Upton, NY]
3 PSI - Paul Scherrer Institute
4 ESRF - European Synchrotron Radiation Facility
5 RU - Rutgers, The State University of New Jersey [New Brunswick]

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 Bi0.31 Ca0.69 MnO3, 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 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.

Mots clés: manganite; resonant x-ray diffraction

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Stéphane Grenier, K. J. Thomas, J.P. Hill, U. Staub, Y. Bodenthin, et al.. Direct probe of oxygen superstructures in manganites. 2007. ⟨hal-00149105v1⟩