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Magnetism and its microscopic origin in iron-based high-temperature superconductors

Abstract

High-temperature superconductivity in the iron-based materials emerges from, or sometimes coexists with, their metallic or insulating parent compound states. This is surprising, as these undoped states exhibit dramatically different antiferromagnetic spin arrangements and Néel temperatures. Although there is a general consensus that magnetic interactions are important for superconductivity, much remains unknown concerning the microscopic origin of the magnetic states. In this review, we summarize the progress in this area, focusing on recent experimental and theoretical results, and their microscopic implications. We conclude that the parent compounds are in a state that is more complex than that implied by a simple Fermi surface nesting scenario, and a dual description including both itinerant and localized degrees of freedom is needed to properly describe these fascinating materials.

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Figure 1: AF structure and spin-wave dispersions for the insulating copper oxide La2CuO4 and the parent compounds of iron-based superconductors BaFe2As2, FeTe and AyFe1.6+xSe2.
Figure 2: The electronic phase diagrams and the evolution of FSs, static AF order and spin excitations on electron or hole doping to BaFe2As2.
Figure 3: Summary of the phase diagram of multiorbital Hubbard models and the electronic state of Fe near the FS.
Figure 4: Sketch of the expected phase diagram of the Hubbard model with varying temperature and U/W in the undoped limit.

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Acknowledgements

We thank L. W. Harriger for preparing the figures shown in this manuscript. We are also grateful to T. A. Maier for calculating the FSs of BaFe2As2 shown in Fig. 2d. P.D. is supported by the US NSF DMR-1063866 (neutron scattering studies on electron-doped iron pnictides), OISE-0968226 (international collaboration) and by US DOE, BES, under Grant No. DE-FG02-05ER46202 (single crystal growth at UTK and neutron scattering studies of hole-doped iron pnictides and other iron-based superconductors). Work at Institute of Physics is supported by the Ministry of Science and Technology of China 973 program (2012CB821400). E.D. is supported by the US DOE, BES, Materials Sciences and Engineering Division and by the US NSF DMR-11-04386.

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P.D. and E.D. wrote the experimental and theoretical portions of the article, respectively. J.P.H. revised the article. All authors discussed the outline of the article.

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Correspondence to Pengcheng Dai or Elbio Dagotto.

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Dai, P., Hu, J. & Dagotto, E. Magnetism and its microscopic origin in iron-based high-temperature superconductors. Nature Phys 8, 709–718 (2012). https://doi.org/10.1038/nphys2438

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