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Research » Spin Logic » Controlling Nanomagnets

Current flowing in heavy metals such as Platinum, Tantalum that exhibit a high Spin Hall angle generates spin currents in the transverse direction, which can control the magnetization direction of ferromagnets in contact with the heavy metals. Such Spin-Orbit Torque (SOT) switching has been the area of interest to create three terminal devices for memory and logic applications.

We have developed sputtering recipes to deposit ultrathin multilayers of β phase-Ta, MgO, Ru and ferromagnetic CoFeB with in-plane and out-of-plane anisotropy. Using the Spin Hall effect of β phase-Ta, we have demonstrated current induced magnetization reversal of CoFeB with perpendicular magnetic anisotropy (PMA). Magnetic layers with perpendicular magnetic anisotropy will enable scaling of spintronics devices down to few nanometers due to their higher thermal stability. We have also shown SOT based switching in Magnetic Tunneling Junctions (MTJ) on Ta(17) | CoFeB(2) | MgO(0.5) | CoFeB(4) | Ru+Ta cap(14) stacks with sizes of 400 x 200 nm². Thick B-phase Tantalum used in these stack compared to usual thicknesses of 5-6 nm will allow integration of the technology on different substrates. (Related publication: AIP Advances 5, 107144 (2015)).

Authors: Ashish Penumatcha, Suprem Das