Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW)
Abstract
By reviewing the experimental and theoretical literature on γ’-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 γ’-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 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
