Abstract
An Fe-Si (6 at%) alloy single crystal has been studied by Mössbauer spectroscopy by varying the magnetization direction relative to the crystal axis ⟨100⟩. The difference spectra ⟨hkl⟩-⟨100⟩ reveal sharp downward spikes in the 1st line (−5 mm/s) and in the 5th line (+3 mm/s) at the position of the main line in the original spectra. Comparing the result with the similar measurement on a pure Fe single crystal, we find that these spikes are caused by Si atoms. The magnitude of each spike was measured as a function of the magnetization direction, and it is ascertained that Si atoms in the 2nd neighbor site play the decisive role to give rise to the spikes. The fact that the spike is present at the main line position confirms the proposal by Cranshaw that the hyperfine field at the probe atom site is not reduced by the Si atom at the second neighbor site.
These results are quantitatively analysed by dipolar as well as quadrupolar shifts of 57Fe Mössbauer transition energies.
