Spatial spin-modulated structure and hyperfine interactions of $^{57}$Fe nuclei in multiferroics BiFe$_{1-x}$T$_{x}$O$_{3}$ ($T$ = Sc, Mn; $x$ = 0, 0.05)

The results of the Mössbauer studies on $^{57}$Fe nuclei in multiferroics BiFe$_{1-x}$T$_{x}$O$_{3}$ ($T$ = Sc, Mn; $x$ = 0, 0.05) in the temperature range of 5.2–300 K have been presented. The Mössbauer spectra have been analyzed in terms of the model of an incommensurate spatial spin-modulated structure of cycloid type. Information has been obtained about the effect of the substitution of Sc and Mn atoms for Fe atoms on the hyperfine parameters of the spectrum: the shift and the quadrupole shift of the Mössbauer line, the isotropic and anisotropic contributions to the hyperfine magnetic field, and also the parameter of anharmonicity of the spatial spin-modulated structure.