Giant anomalous Hall effect in ultrathin Si/Fe bilayers

Anomalous Hall effect studies on ultrathin Si(50Angstrom)/Fe(t_Fe) bilayers were performed at 300 K. Giant enhancements of about 60 times in saturation anomalous Hall resistivity and 265 times in anomalous Hall coefficient (R_s) were observed upon decreasing the Fe layer thickness t_Fe from 200 to 10 Angstrom. The R_s observed for t_Fe = 10 Angstrom is about three orders of magnitude larger than that of bulk Fe. The scaling law between R_s and longitudinal electrical resistivity (Rho) suggests that the side jump is the dominant mechanism of the anomalous Hall effect. The observed largest Hall sensitivity of 433 Ohm/T surpasses that of the semiconducting GaAs and InAs Hall sensors already reported.