Effect of Tm substitution on the magnetic properties and local magnetic anisotropy of amorphous Fe80−xTmxB20 ribbons

We have carried out magnetic and Mössbauer studies of amorphous Fe80−xTmxB20 alloys (0 ≤ x ≤ 16). With an increasing Tm content, both the Curie temperature TC and the magnetic moment of Fe atom μFe decrease. We have extracted the value of exchange constant A from TC and that of the local magnetic anisotropy constant KL from the coercivity. Mössbauer studies were performed in a transmission geometry and also using the conversion electron spectroscopy. Both Mössbauer spectrometry techniques show that the average hyperfine field decreases linearly with the addition of rare-earth.