Comparing Spin-Orbit Torque Switching in All-Ferromagnetic and All-Antiferromagnetic Tunnel Junctions

Magnetic tunnel junctions (MTJs) are technologically relevant spintronic devices that can be used in hardware like magnetic random access memory to minimize energy consumption and maximize information density. MTJs consist of two magnetic electrodes separated by an insulator, where the information is stored by the electrodes’ relative magnetizations. The magnetization is switched by magnetic field or current. In the most efficient method, spin-orbit torque (SOT) switching, current is sent in a wire along one electrode and polarizes via the Spin Hall effect, causing that electrode to switch. The information then can be read by tunneling magnetoresistance (TMR).

To develop next generation hardware, MTJs need ultrafast, low energy switching with high TMR. Typical MTJ electrodes are ferromagnetic (FM), but antiferromagnetic (AFM) electrodes resist external magnetic fields, exhibit ultrafast spin dynamics, and lack stray fields. Theory predicts efficient switching can be obtained in AFM MTJs. However, fabricating such AFM MTJs has been proven difficult. We perform SOT switching on AFM MTJs and FM MTJs and examine the effect of parameters such as pulse width and current density on switching probability.