Resonance-enhanced exchange coupling for voltage-controlled magnetic switching in the scaled magnetic memory device*

We will discuss a voltage-controlled magnetic tunnel junction that uses a resonant tunneling barrier instead of a single oxide barrier. A voltage across the structure leads to a resonant enhancement of the interlayer exchange coupling. The peak equivalent exchange field is strong enough to switch typical ferromagnets used in scaled magnetic memory devices. The resonance-enhanced coupling exhibits a voltage-dependent oscillation that can enable a bidirectional switching with the same voltage polarity, unlike conventional magnetic devices, where a bidirectional current or a magnetic field is necessary. The switching threshold is decoupled from the speed due to the conservative nature of the exerted torque, unlike the conventional spin-torque devices that exhibit a trade-off due to the nonconservative nature of the switching torque. We further show that the magnetoresistance is higher for smaller voltages, while the exchange field is higher for larger voltages—this is promising for efficient read and write operations in potential memory applications.

[1] S. Sayed et al. Phys. Rev. Applied 14, 034070, 2020.