The Hall resistivity of sputtered amorphous Fe-B films

Abstract

Amorphous Fe‐B films were prepared by sputtering in a wide composition range. The magnetization curves at 4.2 K of these amorphous alloys are not saturated easily and the apparent high‐field susceptibility drastically increases with a decrease in boron content. The concentration dependence of magnetization exhibits a broad maximum around 14 %B. The Hall resistivity (ρ_H) as a function of applied magnetic field is also not saturated easily, and this behavior tends to become more significant with decreasing boron content. Such behavior may be correlated with the Invar effects and the stress retained in the amorphous films. The spontaneous Hall coefficient (R_s) calculated from ρ_H has a marked concentration dependence at low boron content, indicating a decrease in the value. The apparent ordinary Hall coefficient R^*_o increases dramatically with decreasing boron content, and also the ordinary Hall coefficient R_o is estimated to exhibit a similar tendency. The present results suggest that the electronic structure of amorphous Fe‐B alloys is analogous to that of crystalline Fe‐Ni Invar alloys.