, III Workshop on Novel Methods for Electronic Structure Calculations

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gamma'-Fe4N: facts and open questions
Stefaan Cottenier

Last modified: 2009-08-26


By reviewing the experimental and theoretical literature on gamma'-Fe4N, and by a systematic survey of predictions by the LDA, PBE, WC, LDA+U (2x), PBE+U (2x) 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 gamma'-Fe4N as found in Nature is exactly at a sharp transition between low-spin and high-spin behaviour. PBE+U (U=0.4 eV) is identified as the most accurate exchange-correlation 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 gamma'-Fe4N is discussed, and is not reproduced by our calculations.

This seminar is based on a review article by Eitel L. Peltzer y Blancá, Judith Desimoni, Niels E. Christensen, Heike Emmerich and SC, Physica Status Solidi B 246 (2009) 909-928 (http://dx.doi.org/10.1002/pssb.200844401).