Current induced magnetization switching, jointly with the manipulation of exchange bias, via spin-orbit torques (SOT) on sub-nanosecond timescales hold great promise for fast and low-power spintronic devices. Speci cally, the time-resolved detection and subsequent analysis of switching trajectories relevant to ferromagnet/antiferromagnet exchange biased structures are central to designing SOT devices with high speed, and are still open questions. Here, we report the SOT-induced multileveled switching on sub-nanosecond timescales in Pt/Co/IrMn heterostructures, and illustrate the time-resolved magnetization switching trajectories of the exchange bias. By adopting time-resolved magneto-optical Kerr microscopy combined with micromagnetic simulations, our work reveals that not only the ferromagnets, but also the multiple antiferromagnetic domains and exchange bias, can be partially switched by sub-nanosecond current pulse, to exibly control the switching probabilities at multiple levels. The experiments demonstrate that the SOT switching of exchange bias, which immediately depends on the current density, can signi cantly stabilize the multileveled magnetization switching within sub-nanosecond current pulse with high thermal stability.
Main TextSpintronic devices based on spin-orbit torques (SOT) have emerged as crucial candidates for future nonvolatile memory devices with low power consumption and high operation speed 1-3 . Developed from the initial SOT devices comprising heavy metal/ferromagnet (FM)/Oxide trilayers 4,5 , the introduction of FM/antiferromagnet (AFM) structures with in-plane exchange bias has extra bene ts. In addition to the advantage of inducing an internal effective eld through the exchange bias effect to enable eld-free SOT switching 6-8 , a second bene t is that optimized structures also provide a exible approach to manipulate the AFM spins through energy-e cient SOT switching 9,10 . The reversal of FM accompanied by the switching of exchange bias also has technological importance for realizing robust magnetization switching with high thermal stability. In view of the intrinsic high frequency response of AFMs 11,12 , gaining insight into the magnetization dynamics as well as into the time-resolved switching process of SOT devices comprising FM/AFM is of great interest, since this lays the scienti c foundation for designing SOT devices with ultrafast switching speed.Recent studies have shown that the perpendicular exchange bias at FM/AFM interfaces can be switched by SOTs, which are either generated from the heavy metal Pt in Pt/Co/IrMn 9 , or from the AFM IrMn in IrMn/CoFeB 10 . The independent manipulation of the perpendicular magnetization and the interfacial exchange bias in the FM/AFM system could improve the plasticity and stability of potential devices towards practical applications. However, these recent experiments have focused on examining the nal magnetic state long after a current pulse has passed, while investigations of the details of magnetization dynamics and in particular the tim...
Current induced magnetization switching, jointly with the manipulation of exchange bias, via spin-orbit torques (SOT) on sub-nanosecond timescales hold great promise for fast and low-power spintronic devices. Specifically, the time-resolved detection and subsequent analysis of switching trajectories relevant to ferromagnet/antiferromagnet exchange biased structures are central to designing SOT devices with high speed, and are still open questions. Here, we report the SOT-induced multileveled switching on sub-nanosecond timescales in Pt/Co/IrMn heterostructures, and illustrate the time-resolved magnetization switching trajectories of the exchange bias. By adopting time-resolved magneto-optical Kerr microscopy combined with micromagnetic simulations, our work reveals that not only the ferromagnets, but also the multiple antiferromagnetic domains and exchange bias, can be partially switched by sub-nanosecond current pulse, to flexibly control the switching probabilities at multiple levels. The experiments demonstrate that the SOT switching of exchange bias, which immediately depends on the current density, can significantly stabilize the multileveled magnetization switching within sub-nanosecond current pulse with high thermal stability.
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