Spontaneous Hall effect and resistivity of Fe-Co-Ni-base glasses

The spontaneous Hall effect and dc resistivity have been measured at room temperature in the glassy alloy series ${\mathrm{Fe}}_{80-x}{\mathrm{Co}}_x{\mathrm{B}}_{20}$ ($0\le x\le 80$ at.%) and ${\mathrm{Fe}}_{80-x}{\mathrm{Ni}}_x{\mathrm{B}}_{20}$ ($0\le x\le 60$ at.%) and in ${\mathrm{Co}}_{40}$ ${\mathrm{Ni}}_{40}$ ${\mathrm{B}}_{20}$ glass. The density-derived thicknesses used herein give smaller values of $R_s$ and $\rho$ than generally reported for metallic glasses. Because of the relatively large resistivities of metallic glasses, $\rho \simeq {10}^{-4\mathrm{}}$ ▪ cm, the nonclassical side-jump mechanism is expected to dominate the spontaneous Hall effect. The magnitude of the side jump in ${\mathrm{Fe}}_{80}$ ${\mathrm{B}}_{20}$ glass is comparable to that in crystalline Fe and Fe-base dilute alloys, viz. ${10}^{-8\mathrm{}}$ cm. The spontaneous Hall conductivity ${\gamma }_{\mathrm{Hs}}$ shows a proportionality to the magnetostriction ${\lambda }_s$ as predicted theoretically with a slope that is close to that observed in crystalline Fe-Ni alloys. The compositional dependence of ${\gamma }_{\mathrm{Hs}}$ is interpreted in terms of a split-band model in which charge is transferred from boron to the transition-metal $d$ states in the glassy alloys. The applicability of the split-band model to these data implies that an intrinsic spin-orbit interaction involving the itinerant $d$ electrons is effective here and not a spin-other-orbit interaction.