Mössbauer Effect Studies in Amorphous TbFe2, DyFe2, HoFe2 and ErFe2

Mossbauer measurements have been performed on sputtered TbFe2, DyFe2, HoFe2 and ErFe2. Neutron diffraction data indicates that sputtered TbFe2 is structurally and magnetically amorphous. At room temperature, sputtered TbFe2 exhibits a Mossbauer pattern which is interpreted as due to a broad distribution of hyperfine fields. A similar distribution of hyperfine fields is observed in DyFe2 and HoFe2 at 77K. DyFe2, HoFe2 and ErFe2 show a resolved doublet at room temperature due to well defined quadrupolar interaction at the iron nuclei. Low temperature measurements on sputtered HoFe2 show the broad pattern at 145K and the quadrupolar doublet at 230K. Our data indicate that the iron moments experience an exchange field of random orientation and magnitude and that the crystal field on the iron ions is relatively uniform.