Magnetization and anomalous Hall effect in SiO2/Fe/SiO2 trilayers

TL;DR

This study investigates SiO2/Fe/SiO2 trilayers, revealing significant enhancement of the anomalous Hall effect and magnetic properties as Fe layer thickness decreases, with implications for spintronic applications.

Contribution

It demonstrates a substantial increase in anomalous Hall resistance and sensitivity in Fe sandwiched films, highlighting the role of nanostructure and thickness in AHE enhancement.

Findings

Maximum R_Ahs of 2.3 Ohm at 50 Å Fe thickness

R_Ahs increased by 14 times when reducing Fe thickness from 300 Å to 50 Å

Scaling law indicates side jump as dominant AHE mechanism

Abstract

SiO2/Fe/SiO2 sandwich structure films fabricated by sputtering were studied by varying the Fe layer thickness (t_Fe). The structural and microstructural studies on the samples showed that the Fe layer has grown in nanocrystalline form with (110) texture and that the two SiO2 layers are amorphous. Magnetic measurements performed with the applied field in in-plane and perpendicular direction to the film plane confirmed that the samples are soft ferromagnetic having strong in-plane magnetic anisotropy. The temperature dependence of magnetization shows complex behavior with the coexistence of both ferromagnetic and superparamagnetic properties. The transport properties of the samples as studied through Hall effect measurements show anomalous Hall effect (AHE). An enhancement of about 14 times in the saturation anomalous Hall resistance (R_Ahs) was observed upon reducing the t_Fe from 300 to 50 Angstrom. The maximum value of R_Ahs = 2.3 Ohm observed for tFe = 50 Angstrom sample is about 4 orders of magnitude larger than that reported for bulk Fe. When compared with the single Fe film, a maximum increase of about 56% in the R_Ahs was observed in sandwiched Fe (50 Angstrom) film. Scaling law suggests that the R_s follows the longitudinal resistivity (Rho) as, R_s proportional to (Rho)^1.9, suggesting side jump as the dominant mechanism of the AHE. A maximum enhancement of about 156% in the sensitivity S was observed.