Structure and magnetic properties of Fe2CoGe synthesized by ball-milling

Iron-based Heusler compounds Fe2YZ: Comparison with theoretical predictions of the crystal structure and magnetic properties

“…These estimates are in fair agreement with the calculated moments of 2.7 µ B and 1.4 µ B for the Fe sites and 0.9 µ B for the Co sites reported in Ref. 15. As for all the present materials the Curie temperatures are above 700 K the estimates of the moments from the room temperature Mössbauer spectra can be used for comparison with theoretical results.…”

“…The experimental magnetic moments of Fe 2 CoGe are quite close to the value of 5 µ B expected from the generalized SlaterPauling (SP) rule. This suggests that Fe 2 CoGe could be a half-metallic ferromagnet, however, the spin polarization appears to be not complete [15](see also Section III). The magnetic moments of all the other materials do not follow the generalized SP rule.…”

“…This leads to a virtual extinction of the (111) and (200) reflections, or at least, to very low intensities, if the standard laboratory sources with Cu-K α or Mo-K α radiation are used. In fact for a well-ordered sample of Fe 2 CoGe very weak superstructure reflections have been observed [15]. Their detection requires, however, an improved signal-to-noise ratio of the XRD patterns and thus considerably longer measurement times.…”

“…To check whether the methodology presented above is suitable for the description of structural and magnetic properties of the Fe 2 YZ materials, first we have performed a set of calculations for Fe 2 CoGe and compared the results with the data already available from the literature [15]. We have considered four different model systems in the cubic structure, where the site occupations were selected with the following configurations: (a) fully ordered Heusler structure; (b) chemically disordered structure (50 % of Fe is mixed with Co); (c) chemically disordered inverse Heusler phase (50 % of the Fe sitting in position C mixed with Co); (d) a fully ordered inverse Heusler structure.…”

“…Motivated by the potential importance of tetragonal iron-based Heusler compounds for applications, especially as potential rareearth free hard magnets, and by the fundamental question of electronic instabilities in Heusler compounds this work reports the synthesis and characterization of the new compounds Fe 2 NiGe, Fe 2 CuGa, and Fe 2 CuAl, the existence of which has been predicted in Ref [14]. In addition the properties of the known phases Fe 2 CoGe [15] and Fe 2 NiGa [16] have been investigated in more detail. Usually first-principle electronic structure calculations are based on a perfect crystal.…”