Implementing Versatile Programmable Logic Functions Using Two Magnetization Switching Types in a Single Device

The efficient manipulation of magnetization using spin-orbit torques (SOTs) generated by heavy metals and topological insulators has attracted significant attention. However, the symmetry of these conventional materials makes it challenging to achieve deterministic switching of perpendicular magnetization by currents, which prevents the practical application of SOT-based spintronic devices such as magnetic memories and logics. Here, a composition gradient in a Ta_xTi_1-x alloy is introduced and the field-free magnetization switching in Ta_xTi_1-x/CoFeB heterostructures with controllable SOT efficiencies is realized. Additionally, by engineering the gradient with a tilting angle relative to the current injection arm of the device, highly asymmetric switching loops are achieved, which are attributed to tilted spin polarization. Based on these two switching types, namely field-free switching and field-assisted asymmetric switching, five programmable Boolean logic functions are successfully demonstrated using a single device. This work paves the way for high-density computing-in-memory applications with industry compatible artificially-designed asymmetric SOT materials.