Two-current model of the composition dependence of resistivity in amorphous (Fe_100−xCo_x)_89−yZr₇B₄Cu_y alloys using a rigid-band assumption

Composition dependence of resistivity is studied in amorphous (Fe_100−xCo_x)_89−yZr₇B₄Cu_y (0 ≤ x ≤ 50, y = 0, 1) alloys. The two-current model proposed by Mott for crystalline materials is extended to a disordered amorphous system where s-d scattering is dominant in electron conduction. A rigid-band assumption is made due to the small atomic number difference between Fe and Co. Band structures with a constant density of states (DOS), parabolic distributed DOS, and Gaussian distributed DOS were investigated to fit experimental data. The Gaussian distributed DOS was found to simulate the resistivity maximum and magnetic moment maximum in the Fe-rich region. The basic concepts presented here can potentially provide insight into the optimization of FeCo-based HITPERM alloys for applications at increased frequencies.