Temperature dependence of the electrical resistivity in some amorphous ferromagnetic alloys

Temperature coefficient of the resistivity and crystallization are studied in Fe_100-xB_x, Fe_80-xCo_xB₂₀, Fe₇₈B_22-xSi_x and Fe_100-xB_x-ySi_y amorphous alloys. From the comparison of the theory with experimental data, the structure factors for these alloys were evaluated. The sharp drop of the resistivity at crystallization temperature increases with Fe content and decreases with Si content. During the measurements the Debye temperature could vary for a given sample. This variation is considered to be produced by changes in microstructure of the amorphous sample which are induced by thermal activation during thermal treatments. An irreversible change of the short-range order is attained which is related to an irreversible decrease of the free volume. Simultaneously, a reversible modification of this order is interpreted as due to reorientation of atomic chemical bonds.