Current-driven magnetization switching in CoFeB/MgO/CoFeB magnetic tunnel junctions

TL;DR

This paper reports on low-current magnetization switching in CoFeB/MgO/CoFeB magnetic tunnel junctions, highlighting the effects of annealing on tunnel magnetoresistance and critical current densities, with implications for spintronic device efficiency.

Contribution

It demonstrates low critical-current densities for switching in CoFeB/MgO/CoFeB MTJs and analyzes how annealing affects TMR ratios and switching currents.

Findings

Critical current densities as low as 7.8 x 10^5 A/cm^2 achieved

TMR ratios increase with annealing temperature, reaching 160%

Low Jc attributed to high spin polarization and small MsV product

Abstract

Current-driven magnetization switching in low-resistance Co40Fe40B20/MgO/Co40Fe40B20 magnetic tunnel junctions (MTJs) is reported. The critical-current densities Jc required for current-driven switching in samples annealed at 270C and 300C are found to be as low as 7.8 x 10^5 A/cm^2 and 8.8 x 10^5 A/cm^2 with accompanying tunnel magnetoresistance (TMR) ratios of 49% and 73 %, respectively. Further annealing of the samples at 350C increases TMR ratio to 160 %, while accompanying Jc increases to 2.5 x 10^6 A/cm^2. We attribute the low Jc to the high spin-polarization of tunnel current and small MsV product of the CoFeB single free layer, where Ms is the saturation magnetization and V the volume of the free layer.