Transverse spin freezing in the vicinity of amorphous Fe

Temperature dependence of magnetism in the vicinity of the ferromagnetic instability point of amorphous Fe has been investigated on the basis of the finite temperature theory of amorphous metallic magnetism which takes into account the transverse spin degrees of freedom. The theory is based on the functional integral technique to the degenerate-band Hubbard Hamiltonian and the distribution function method for local magnetic moments with structural disorder. Numerical calculations have been performed with decreasing temperature near the boundary between the ferromagnetic and the spin glass phases. It is shown that the amorphous metals around Fe exhibit the transition from the collinear to the noncollinear ferromagnetic state at a temperature lower than the Curie temperature, due to the freezing of transverse spin components. The present results are consistent with those of recent Mossbauer measurements on Fe-rich amorphous transition metal alloys. (C) 2000 American Institute of Physics. [S0021-8979(00)67508-4].