Variation of Hall Coefficient of Some Non-ferromagnetic Superlattice Alloys

Abstract

The temperature dependence of Hall coefficient of five superlattice alloys of Cu₃Pd, CuZn, Ni₃Cr, Au₃Cu and Ag₃Mg was measured to find the effect of order-disorder transformation upon it. At the transition temperature, the Hall coefficient of Cu₃Pd and Ag₃Mg showed a discontinuous change, while the change of Hall coefficient of other three alloys (CuZn, Ni₃Cr, Au₃Cu) are very small. Applying Muto’s theory, the qualitative discussion was made, and it was found that the general features of the temperature dependence of CuZn and Ni₃Cr are well understood by the theory. For Au₃Cu, the result of the experiment is explained by adopting the assumption of Schubert that each Au atom affords more than one electrons into the conduction band. The assumption also explains why the temperature dependence of Hall coefficient of Au₃Cu differs from that of Cu₃Au.
It remains unknown why Hall coefficient of Cu₃Pd takes strong minimum at transition temperature, while the abrupt increase of the Hall coefficient with the decreasing temperature below T_c can be explained by the existence of a superzone in the ordered state. In addition, the result Ag₃Mg is contrary with that which Nicholas’s theory suggested.