Letter | Published:

Effects of electron correlations on transport properties of iron at Earth’s core conditions

Nature volume 517, pages 605607 (29 January 2015) | Download Citation

  • This article was retracted on 13 April 2016

Abstract

Earth’s magnetic field has been thought to arise from thermal convection of molten iron alloy in the outer core, but recent density functional theory calculations have suggested that the conductivity of iron is too high to support thermal convection1,2,3,4, resulting in the investigation of chemically driven convection5,6. These calculations for resistivity were based on electron–phonon scattering. Here we apply self-consistent density functional theory plus dynamical mean-field theory (DFT + DMFT)7 to iron and find that at high temperatures electron–electron scattering is comparable to the electron–phonon scattering, bringing theory into agreement with experiments and solving the transport problem in Earth’s core. The conventional thermal dynamo picture is safe. We find that electron–electron scattering of d electrons is important at high temperatures in transition metals, in contrast to textbook analyses since Mott8,9, and that 4s electron contributions to transport are negligible, in contrast to numerous models used for over fifty years. The DFT+DMFT method should be applicable to other high-temperature systems where electron correlations are important.

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Acknowledgements

This work is supported by National Science Foundation (NSF) grants EAR-1214807, DMS-1025392, and DMR-1405303. R.E.C. is supported by the Carnegie Institution and the European Research Council Advanced Grant ToMCaT. K.H. is supported by NSF grant DMR-1405303. This research used the NSF Extreme Science and Engineering Discovery Environment (XSEDE) supercomputer ‘Stampede’, and also used the resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the US Department of Energy under contract number DE-AC05-00OR22725. R.E.C. and P.Z. thank I. Mazin, S. Labrosse and R. Caracas for discussions. We also acknowledge J. Robb for assistance with the manuscript preparation.

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Affiliations

  1. Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington DC 20015, USA

    • Peng Zhang
    •  & R. E. Cohen
  2. Department of Earth Sciences, University College London, 222 Pearson Building, Gower Street, London WC1E 6BT, UK

    • R. E. Cohen
  3. Department of Physics, Rutgers University, Piscataway, New Jersey 08854, USA

    • K. Haule

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Contributions

R.E.C. designed the project, P.Z. performed the computations, P.Z., R.E.C. and K.H. analysed the results and prepared the paper. The DFT + DMFT code was developed by K.H.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to R. E. Cohen.

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https://doi.org/10.1038/nature14090

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