Giant anomalous Hall effect in ultrathin Si/Fe bilayers

TL;DR

This study reports a giant anomalous Hall effect in ultrathin Si/Fe bilayers, with significant enhancements in Hall resistivity and coefficient, revealing a dominant side jump mechanism and potential for high-sensitivity magnetic sensors.

Contribution

It demonstrates a substantial increase in anomalous Hall effect in ultrathin Si/Fe bilayers and identifies the side jump as the dominant mechanism, surpassing existing sensor sensitivities.

Findings

Hall resistivity increased 60-fold with decreasing Fe thickness

Anomalous Hall coefficient (R_s) increased 265-fold, reaching three orders of magnitude larger than bulk Fe

Hall sensitivity of 433 Ohm/T exceeds that of existing GaAs and InAs Hall sensors

Abstract

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.