Interpretation of Mössbauer Spectra of β-FeB and Its Low Temperature Modification, α-FeB

Both α and β modifications of FeB are ferromagnetic, and their Curie temperatures and saturation magnetizations are nearly the same, while their Mössbauer spectra are different each other. In order to clarify the origin of these differences, the Mössbauer effect of both α- and β-FeB is measured under an external magnetic field of 4.0 T. The results obtained indicate that both α- and β-FeB reveal anisotropic hyperfine fields. The distribution of the hyperfine field observed in the α-FeB is discussed on the basis of an anisotropic hyperfine field as well as the proposed crystal structure.