Magnetic ordering in amorphous and crystallized Fe_x-Ge_1-x films

Abstract

Magnetic ordering in amorphous a-Fe_x-Ge_1-x thin films, in the composition range 0.10≤x ≤0.60, deposited at room temperature (300 K), has been studied using Mssbauer spectroscopy, Curie termperature, and Lorentz electron microscopy observations. The absence of magnetic ordering was noted in a-Fe_x-Ge_1-x films for x<0.40 down to 4.2 K. The onset of long-range magnetic ordering occurs at x≅0.5 even at room temperature. However, Fe_x-Ge_1-x films for x≥0.50 were found to be polycrystalline in nature. The absence of ferromagnetic ordering for x≤0.40 is consistent with the rather small magnetic moment of Fe in the amorphous phase. The Fe_x-Ge_1-x films for x≥0.50 were found to contain the various intermetallics of Fe-Ge binary. In these intermetallics, Fe is known to possess a large magnetic moment and thereby the long-range magnetic ordering is being observed in these films.