The Hall Effect of Copper-Nickel Alloys

The ordinary and extraordinary Hall effects have been measured at room temperatures for the N-Cu series of alloys. The number of conduction electrons calculated from n*=1R₀Nec (where R₀ is the "ordinary" constant measured at high fields) agrees fairly well with the number of $4s$ electrons predicted for the alloys from the simple band model. It is shown that the agreement for these alloys should improve at lower temperatures. Results in pure nickel and copper do not agree so well. A two-band model is invoked to explain the ordinary effect in pure nickel. Since in pure copper the $4s$ band is half-full, the simple approximation, valid for nearly empty bands, should not be expected to hold. No explanation is offered for the extraordinary Hall effect in any of the samples.