Abstract
Electric field is an energy-efficient tool that can be leveraged to control spin–orbit torques (SOTs). Although the amount of current-induced spin accumulation in a heavy metal (HM)/ferromagnet (FM) heterostructure can be regulated to a certain degree using an electric field in various materials, the control of its direction has remained elusive so far. Here, we report that both the direction and amount of current-induced spin accumulation at the HM/FM interface can be dynamically controlled using an electric field in an oxide capped SOT device. The applied electric field transports oxygen ions and modulates the HM/FM interfacial chemistry resulting in an interplay between the spin Hall and the interfacial torques which in turn facilitates a non-volatile and reversible control over the direction and magnitude of SOTs. Our electric-field controlled spin-orbitronics device can be programmed to behave either like the SOT systems with a positive spin Hall angle or a negative spin Hall angle.
Highlights
Electric field is an energy-efficient tool that can be leveraged to control spin–orbit torques (SOTs)
The direction of this spin accumulation is an important parameter in the design of SOT applications such as the magnetic random access memory (MRAM), domain wall memory and skyrmion-based memory as it determines the direction of magnetization switching, domain wall motion and skyrmion motion
For the case of initial device state before application of any gate voltage (Vg), the sign of the second harmonic peaks (SHpeaks) in Fig. 1e is consistent with the SOT direction from a typical Pt underlayer[7], corresponding to a positive effective spin Hall angle or SOT efficiency, ξSOT due to the damping-like torque
Summary
Electric field is an energy-efficient tool that can be leveraged to control spin–orbit torques (SOTs). We report that both the direction and amount of current-induced spin accumulation at the HM/FM interface can be dynamically controlled using an electric field in an oxide capped SOT device. 1234567890():,; In a HM/FM heterostructure, current-induced spin accumulation[1,2,3,4,5] at the HM/FM interface arises from the bulk spin Hall effect (SHE)[2,6,7,8,9] and/or from the interfacial spin–orbit coupling[1,6,7,8,9] The direction of this spin accumulation is an important parameter in the design of SOT applications such as the magnetic random access memory (MRAM), domain wall memory and skyrmion-based memory as it determines the direction of magnetization switching, domain wall motion and skyrmion motion. Our findings will offer a substantial improvement to the SOT based memory scheme as well as create opportunities for novel applications such as spin-logic circuits and programmable spin-circuits[22]
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