Mössbauer Effect Studies in Amorphous TbFe2, DyFe2, HoFe2and ErFe2

Mossbauer measurements have been performed on sputtered TbFe 2 , DyFe 2 , HoFe 2 and ErFe 2 . Neutron diffraction data indicates that sputtered TbFe 2 is structurally and magnetically amorphous. At room temperature, sputtered TbFe 2 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 DyFe 2 and HoFe 2 at 77K. DyFe 2 , HoFe 2 and ErFe 2 show a resolved doublet at room temperature due to well defined quadrupolar interaction at the iron nuclei. Low temperature measurements on sputtered HoFe 2 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.