Hall Effect and Transverse Magnetoresistance in Some Ferromagnetic Iron-Chromium Alloys

The two Hall coefficients, ${R_0}^{*}$ and ${R_s}^{*}$, and the transverse magnetoresistance were measured for five alloys containing nominally 0.75, 2.3, 5.1, 12.7, and 25.1 at.% chromium in iron, at temperatures ranging from that of boiling helium to room temperature. For all compositions and temperatures both ${R_0}^{*}$ and ${R_s}^{*}$ were positive. ${R_0}^{*}$ increases smoothly as the electron concentration passes through that of pure iron into lower concentrations, and reaches a maximum near 12.7% Cr (25.7 e/atom). No sharp maximum in ${R_0}^{*}$ was found at pure iron as had previously been found for pure Ni and pure Co. This behavior is shown to be consistent with a simple band picture, although the detailed interpretation of the data is uncertain because of the complicated multiband structure in the pure-iron region. The observed sign and magnitudes of the ordinary constant do show the importance of the hole conduction in the $3d$ sub-band relative to the electronic conduction in the $4s$ band. The behavior of ${R_s}^{*}$ as a function of resistivity $\rho$ is found to agree with the theories that predict a ${\rho }^2$ dependence in the more concentrated alloys and also in the dilute alloys in the higher temperature region (above ∼100°K). Determinations of the high-field slopes of the transverse-magneto-resistance curves were made. The data appeared linear within the accuracy of the observations.