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Abstract:
Recent spin echo nuclear magnetic resonance (NMR) revealed that the
half-metallic Co(2)Mn(1-x)Fe(x)Si Heusler alloys exhibit the L2(1)
structure with random distribution of Mn and Fe on the 4b Wyckoff
position. This random distribution is most prominent in the third
coordination shell of the (55)Mn nuclei, as this shell is the first
magnetically active shell, leading to a line splitting in the (55)Mn NMR
spectra. A comparison, as presented in this paper, of all (55)Mn NMR
satellite lines shows that the resonance frequencies corresponding to
the same number of Fe atoms in the third shell of (55)Mn shift to
slightly different resonance frequencies with increasing overall Fe
content x. This shift is related to the constructive contribution of
higher shells to the hyperfine field. These higher shells affect also
the satellite linewidth, leading to a parabolic behavior with increasing
Fe concentration x. This parabolic behavior is modified by the frequency
spacing related to the replacement of Mn by Fe. (C) 2008 American
Institute of Physics.
