Mössbauer Studies of Iron-Rare Earth Intermetallics

Abstract

The Mössbauer effect has been used to study the hyperfine field at the Fe sites of DyFe₂, HoFe₂, ErFe₂, TbFe₂, and SmFe₂. The last three of these each show two superimposed hyperfine spectra with an intensity ratio of about 3:1. A similar result was found for ZrFe₂ and TmFe₂ by Wertheim et al.,¹ who showed that it was consistent with the magnetization lying along a (111) direction. In DyFe₂ and HoFe₂ however we find only one Fe hyperfine spectrum at room temperature; it is shown that this would be expected if the magnetization is along a (100) direction. An explanation of these results is given on the basis of a simple ferromagnetic (antiferromagnetic) model for the light (heavy) rare earth intermetallics in which the direction of magnetization is determined by the easy direction for the rare earth ion. The hyperfine fields at the Fe and Dy sites in DyFe₂ have also been measured as a function of temperature. This parallels the work of Cohen² on TmFe₂ and allows a comparison of the rare earth‐iron exchange in these intermetallics.