Magnetic ordering in amorphous and crystallized Fe<SUB>x</SUB>-Ge<SUB>1-x</SUB> films

Magnetic ordering in amorphous a-Fex-Ge1-x thin films, in the composition range 0.10&#8804;x &#8804;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-Fex-Ge1-x films for x&lt;0.40 down to 4.2 K. The onset of long-range magnetic ordering occurs at x&#8773;0.5 even at room temperature. However, Fex-Ge1-x films for x&#8805;0.50 were found to be polycrystalline in nature. The absence of ferromagnetic ordering for x&#8804;0.40 is consistent with the rather small magnetic moment of Fe in the amorphous phase. The Fex-Ge1-x films for x&#8805;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