3d moment

From a comparison with RECr4Al8 and REMn4Al8 compounds, in which the presence of 3d-moments is manifest (Felner and Nowik 1979), one may derive that... 

Experimental magneto-optical data obtained by van Engelen and Buschow have been reproduced in fig. 42 where the data for R2Fe14B and R2Co14B can be compared with the magneto-optical properties of the pure transition metals Fe and Co. In the Co compounds the 3d-moments are substantially reduced upon com-... 

Similar studies of the a-Mn alloys (70-95 at. % Mn) show fields of 5 and 16 kG at the two site symmetries occupied by iron with little or no dependence on manganese concentrations. The aligned 3d-moment on the iron atoms must therefore be small [44]. 

Fig. 48. Concentralion dependence of the 3d moments in crystalline and amorphous Y, COj, (left-hand part) and Yj j Fej, (right-hand part). The circles and full curves refer to amorphous alloys. The squares and broken curves refer to intermetallics. The data of Y, j Fe were taken from Coey et al. (1981).

As a consequence one would expect the magnetic 3d moment in amorphous alloys to be lower than in crystalline materials. This seems to be in disagreement with experiment (see the compilation of data given by Buschow, 1982d). 

The conclusions arrived at in the photoemission studies described above are in agreement with similar conclusions reached by Azoulay and Ley (1979) for crystalline Gd-Fe compounds. The photoemission results do not reveal major differences in electronic structure between crystalline and amorphous alloys of similar composition, but they make it clear that the reduction in 3d moment in both classes of materials is mainly due to a reduction in 3d band exchange splitting. In conclusion, charge transfer does occur upon alloying but it is too small to account for the changes in 3d moment observed. 

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