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(π, π) electronic order in iron arsenide superconductors


The distribution of valence electrons in metals usually follows the symmetry of the underlying ionic lattice. Modulations of this distribution often occur when those electrons are not stable with respect to a new electronic order, such as spin or charge density waves. Electron density waves have been observed in many families of superconductors1,2,3, and are often considered to be essential for superconductivity to exist4. Recent measurements5,6,7,8,9 seem to show that the properties of the iron pnictides10,11 are in good agreement with band structure calculations that do not include additional ordering, implying no relation between density waves and superconductivity in these materials12,13,14,15. Here we report that the electronic structure of Ba1-xK x Fe2As2 is in sharp disagreement with those band structure calculations12,13,14,15, and instead reveals a reconstruction characterized by a (π, π) wavevector. This electronic order coexists with superconductivity and persists up to room temperature (300 K).

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Figure 1: Fermi surface topology of Ba1- xKxFe2As2.
Figure 2: Low-energy electronic structure of Ba1- xKxFe2As2.
Figure 3: (π, π) reconstruction of the electronic structure.
Figure 4: Blade structure at X.


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The project was supported, in part, by the Deutsche Forschungsgemeinschaft under grant numbers KN393/4 and BO 1912/2-1. We are grateful to I. Eremin, O. K. Andersen, L. Boeri, I. Mazin and M. Rümelli for discussions. We thank R. Hübel for technical support.

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Correspondence to S. V. Borisenko.

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Zabolotnyy, V., Inosov, D., Evtushinsky, D. et al. (π, π) electronic order in iron arsenide superconductors. Nature 457, 569–572 (2009).

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