Abstract
The magnetic moments per Fe atom in the high-T c iron-based superconducting compounds BaFe2As2 and LaFeAsO obtained from first-principles calculations with the local-spin-density approximation are much larger than those obtained from experiments. To resolve the contradictory results between theory and experiment we employed the so-called +U technique with negative U in the first-principles calculation. The calculated values with negative U, −0.09 Ry and −0.10 Ry for BaFe2As2 and LaFeAsO, respectively, are in excellent agreement with the experimental ones. By comparing the differences in the d-orbital occupation numbers and spin densities calculated by using a simple Generalized-Gradient approximation (GGA) and the GGA+U with negative U, we found the magnetic moments of the two compounds to be similar to the case of the low-spin state of the metamagnetic Fe3Al alloy.
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Jang, J.K., Rhee, J.Y. Magnetic states of iron-based superconducting compounds: A comparative study with Fe3Al alloy. Journal of the Korean Physical Society 66, 646–650 (2015). https://doi.org/10.3938/jkps.66.646
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DOI: https://doi.org/10.3938/jkps.66.646