The magnetic properties of amorphous AlxFe100−x alloys investigated by the atomic structure, magnetoresistance and anomalous Hall effect

Abstract

We report on experimental results of the specific resistivity ρ, Hall resistivity ρH and magnetoresistance MR of rapidly quenched AlxFe100−x binary amorphous alloys. Atomic structure investigation done by transmission electron microscopy at room temperature verifies that samples are in the pure amorphous state with a high coordination number 8<Nc<12. Systematic changes in the resistivity, magnetoresistance and Hall effect were observed with the varying Fe content. At room temperature, samples with Fe content ⩾40% show negative magnetoresistance, are p-type and show the presence of anomalous Hall effect, while samples with Fe content ⩽25% show positive magnetoresistance, are n-type and show no anomalous Hall effect contribution. Our experimental results are discussed in the concept of electronic stabilization Hume-Rothery amorphous alloys triggered by the hybridization effect of the Fe-d and the Al-s,p electrons. Previous literature results have predicted that when the Fe-d states are full, no ferromagnetic properties should be observed in the AlxFe100−x alloys, and this is for concentrations x⩾75, which is in agreement with our results, because the appearance of an anomalous contribution in the Hall effect would be a direct evidence of ferromagnetic order in the AlxFe100−x amorphous alloys.