Magnetic interactions in amorphous Fe-Sc alloys

Results of Fe-57 Mbssbauer spectroscopy, AC and DC susceptibility, grazing incidence X-ray diffraction and Rutherford-backscattering measurements on the amorphous alloys Fe100-xScx(8 less than or equal tox less than or equal to 70) give for the first time, convincing evidence for the antiferromagnetic exchange coupling between Fe moments at low Sc concentrations. This antiferromagnetic coupling for 8 less than or equal tox less than or equal to 20 is limited to certain regions (magnetic clusters) of the sample. The nature of the coupling is of the Heisenberg type. For x>43, the positive magnetic coupling between the Fe moments is across Sc atoms. The ferromagnetic coupling between Fe atoms can be explained by the superexchange. Sc moments couple antiferromagnetically to the Fe nearest neighbors. (C) 2001 Elsevier Science B.V. All rights reserved.