Electronic transport in amorphous Ni-P alloys

We have measured the resistivity p(T) and the thermoelectric power S(T) in the metallic glass system Ni_1-xP_x, with 0.10<×<0.25. S(T) increases with increasing phosphorus concentration and changes sign, becoming positive above x=0.18. The S(T) is not linear over the entire measured temperature range for any of the samples. The samples with lowest x (x=0.142, 0.171) have negative S(T) with large positive curvatures which produce broad minima in SQ. This is also the ferromagnetic range of composition. Samples of intermediate-phosphorus content (x=0.176, 0.180) have small S(T) with both positive and negative curvatures in different temperature ranges. These compositions are near the transition from ferromagnetic to paramagnetic behaviour. Samples with large x (x=0.197,0.200,0.214,0.220 and 0.245) have positive S(T) with negative curvatures. In this range of compositions S(T) fits a power law in T, S(T)=CT^B. We find that as x increases, ρ increases, α [α=(1/ρ)dρ/dT] decreases and becomes negative, and S increases and becomes positive near x=0.18. These results agree with the Mooiji correlation and with a correlation of S>0 with high ρ and S<0 with low ρ, which is also seen in many nonmagnetic metallic glasses. Thus the Ni_1-xP_x system spans the range of behaviour seen in many different metallic glasses. For x< 0.175, ρ(T) and S(T) are very similar to those seen in iron-based ferromagnetic glasses. The only clear difference between the transport properties of samples prepared by melt quenching and chemical deposition is in the temperature dependence of α. We compare our results with several theories for electron scattering