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

We report on experimental results of the specific resistivity., Hall resistivity rho(H) 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 < N-c < 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.