Ferromagnetic Hall Coefficient of Nickel Alloys

Published Hall coefficient data for binary Ni alloys have been examined in light of the Karplus-Luttinger theory of the ferromagnetic Hall effect. This theory indicates that the extraordinary Hall coefficient is related to the square of the electrical resistivity, R₁=Aρ². Neither the exponent nor the coefficient of ρ varies as additions of up to 30 atomic percent Cu are made to pure Ni, and as the temperature is varied from 20^∘{}K to 290^∘{}K. On the other hand, small additions of either Al, Si, or Sn to Ni cause a significant variation in A, but appear to leave the exponent of ρ unaltered. A tentative explanation is offered for the difference in behavior.