Enhancement of anomalous Hall effect in Si/Fe multilayers

TL;DR

This study demonstrates a significant enhancement of the anomalous Hall effect in Si/Fe multilayers at room temperature, with the effect strongly dependent on Fe layer thickness, suggesting potential for advanced Hall sensors.

Contribution

It reports the first large enhancement of anomalous Hall effect in Si/Fe multilayers, highlighting the role of interfaces and layer thickness in optimizing Hall sensitivity.

Findings

Hall resistance increased by 60 times with thinner Fe layers.

Anomalous Hall coefficient was up to 1.4 x 10^-7 Ohm m/T, three orders larger than pure Fe.

Hall sensitivity improved by three orders of magnitude, indicating potential for sensor applications.

Abstract

Anomalous Hall effect studies were performed at 300 K on Si/Fe multilayers prepared by dc magnetron sputtering. About 60 times enhancement in the saturation Hall resistance and 80 times enhancement in anomalous Hall coefficient are obtained in [Si(50 angstrom)/Fe(tFe)]_20 multilayers when decreasing the Fe layer thickness from 100 Angstrom to 20 Angstrom. The largest anomalous Hall coefficient (Rs) of 1.4 x 10^-7 Ohm m/T was found for t_Fe=20 Angstrom, which is about three orders of magnitude larger than that of pure Fe and Fe/Cr, Al/Fe, Cu/Fe, SiO2/FePt/SiO2 multilayers. The ordinary Hall coefficient R_0 was about two orders of magnitude larger than that of pure Fe. The R_s was found to vary with the longitudinal electronic resistivity, Rho as R_s proportional to (Rho)^2.2, indicating the role of interfaces for the enhancement of the anomalous Hall effect in the multilayers. An increase of Hall sensitivity from 9 mOhm/T to 1.2 Ohm/T is observed on decreasing tFe from 100 Angstrom to 10 Angstrom. The high Hall sensitivity obtained is about three orders of magnitude larger than that of Al/Fe and Cu/Fe multilayers, showing it as an emerging candidate for Hall element for potential applications.