Magnetically driven suppression of nematic order in an iron-based superconductor.
A theory of superconductivity in the iron-based materials requires an understanding of the phase diagram of the normal state. In these compounds, superconductivity emerges when stripe spin density wave (SDW) order is suppressed by doping, pressure or atomic disorder. This magnetic order is often pre-empted by nematic order, whose origin is yet to be resolved. One scenario is that nematic order is driven by orbital ordering of the iron 3d electrons that triggers stripe SDW order. Another is that magnetic interactions produce a spin-nematic phase, which then induces orbital order. Here we report the observation by neutron powder diffraction of an additional fourfold-symmetric phase in Ba1-xNaxFe2As2 close to the suppression of SDW order, which is consistent with the predictions of magnetically driven models of nematic order.
1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA [2].
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Avci
1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA [2] Department of Physics, Northern Illinois University, DeKalb, Illinois 60115, USA.
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Chmaissem
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Allred
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Rosenkranz
Institut für Theoretische Physik III, Ruhr-Universität Bochum, 44801 Bochum, Germany.
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Eremin
Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
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Chubukov
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Bugaris
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Chung
1] Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA [2] Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
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Kanatzidis
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Castellan
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Schlueter
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Claus
ISIS Pulsed Neutron and Muon Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX, UK.
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Khalyavin
ISIS Pulsed Neutron and Muon Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX, UK.
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Manuel
ISIS Pulsed Neutron and Muon Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX, UK.
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Daoud-Aladine
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845, USA.
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Osborn