Spin-transfer torque switching at ultra low current densities

TL;DR

This paper reports achieving the lowest known current density for magnetization switching in magnetic tunnel junctions by optimizing layer structures, highlighting the role of tantalum buffers and boron transport.

Contribution

It demonstrates that specific layer engineering reduces switching current density to record lows, advancing low-power spintronic device development.

Findings

Critical switching current density as low as 9.2 kA/cm²

Tantalum buffer layer influences magnetic anisotropy

Boron transport affects switching currents

Abstract

The influence of the tantalum buffer layer on the magnetic anisotropy of perpendicular Co-Fe-B/MgO based magnetic tunnel junctions is studied using magneto-optical Kerr-spectroscopy. Samples without a tantalum buffer are found to exhibit no perpendicular magnetization. The transport of Boron into the tantalum buffer is considered to play an important role on the switching currents of those devices. With the optimized layer stack of a perpendicular tunnel junction, a minimal critical switching current density of only 9.2 kA/cm$^2$ is observed. As of today, this value is the lowest reported value for current-induced magnetization reversal.