Electric and magneto-ionic switching of magnetic tunnel junctions

Magnetic tunnel junctions (MTJs) play a key role in modern memory and spintronic technology. Electric field switching of MTJs has been intensely pursued, with the potential of substantially lowering the energy consumption. This includes the utilization of spin-transfer torque (STT),¹ spin-orbit toque (SOT),² and multiferroic insulating layers,³ which can still be limited by high electric currents and reliance on external magnetic fields. Here, we report on electric field control of the tunnelling magnetoresistance (TMR) in MTJs using the magneto-ionic effect. The CoFeB/MgO/CoFeB based MTJs exhibit an initial perpendicular TMR of ~ 3.5% through the insulating MgO barrier layer. With a GdO_x layer placed on top of the free magnetic layer and providing a source of O ions, TMR can be suppressed below noise levels after E-field application and recovered by reversing the E-field polarity. These transport measurements, along with N-vacancy center magnetometry, and energy dispersive X-ray spectroscopy allowed for insight into structural and magnetic changes produced by the magneto-ionic effect. These results highlight the potential of energy-efficient electric and magneto-ionic switching of MTJ devices.

References

¹Z. Diao, et al., . Phys. Condens. Matter 19, 165209 (2007).

²M. Wang, et al.,, Nat. Electron. 1, 582–588 (2018).

³P. S. Li, et al., Adv. Mater. 26, 4320–4325 (2014).