The magnetization of γ′-Fe4N: theory vs. experiment

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  • Eitel L. Peltzer y Blancá, GEMyDE, Facultad de Ingeniería, Argentina
  • Judith Desimoni, Departamento de Física, Facultad de Ciencias Exactas, Argentina
  • Niels Egede Christensen
  • Heike Emmeric, RWTH Aachen University, Germany
  • Stefaan Cottenier, Katholieke Universiteit Leuven, Ghent University, Belgium
  • Department of Physics and Astronomy
  • Interdisciplinary Nanoscience Center
  • Teoretisk naturvidenskab

By reviewing the experimental and theoretical literature on γ′-Fe4N, and by a systematic survey of predictions by the LDA, PBE, WC, LDA + U (2×), PBE + U (2×) and B3PW91 exchange-correlation functionals, the structural, magnetic and hyperfine properties of this material as well as their pressure dependencies are interpreted. The hypothesis is put forward that γ ′-Fe4N as found in Nature is exactly at a steep transition between low-spin and high-spin behaviour. PBE + U (U = 0.4 eV) is identified as the most accurate exchangecorrelation functional for this material, although it is needed to fix the magnetization at the experimental value to obtain a satisfying description. Remaining disagreement between theory and experiment is pointed out. A recent experimental claim for a giant magnetic moment in γ ′-Fe4N is discussed, and is not reproduced by our calculations. We expect that the new insight obtained in the present work can lead to a consistent ab initio modeling of other materials in the iron-nitrogen binary system. In an accompanying didactic section, the physics behind some common exchange-correlation functionals is outlined.

Original languageEnglish
JournalIPPS physica status solidi (b)
Volume246
Issue5
Pages (from-to)909-928
ISSN0370-1972
DOIs
Publication statusPublished - 19 Mar 2009

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