We investigated tunnel magnetoresistance (TMR) and magnetization switching due to spin-transfer torque in CoFeB/MgO/CoFeB junctions having three different free layer compositions, (Co50Fe50)100-xB x (x = 20, 25, 30), and measured their magnetic properties, including magnetization (Ms) and Gilbert damping constant (α), which are theoretically predicted to contribute to the critical current density (J c0) for spin-transfer switching. We found that the Jc0 in the magnetic tunnel junctions (MTJs) with x = 30 became smaller than that in the MTJs with x = 20 despite having a lower TMR ratio and a larger α. We showed that the Jc0 for each composition tends to follow the theoretical relationship for the magnetic factor of the free layer.
ASJC Scopus subject areas
- Physics and Astronomy(all)