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technical paper
Voltage driven Gigahertz Frequency Modulation in Spin Hall Nano
Abstract Body Spin Hall nano-oscillators (SHNOs) exploiting spin current-driven magnetization auto-oscillation have received much attention because of their high potential for neuromorphic applications. In particular, SHNOs provide large-scale mutual synchronization and individual control of the oscillation frequency using a gate voltage. However, the voltage-driven frequency modulation is in the megahertz range, which is not sufficient to train oscillators in response to a wide range of the input signals in the oscillatory neural network. Here, we show that the frequency of SHNO can be controlled up to 2.1 GHz by a moderate electric field of 1.25 MV/cm. The large frequency modulation is attributed to the voltage-controlled magnetic anisotropy (VCMA) in a perpendicularly magnetized Pt/Co/Nin/AlOx structure. Moreover, non-volatile VCMA effect enables control of the cumulative frequency by repetitive pulses, which can mimic the potentiation and depression functions of biological synapses 1. Our results suggest that the voltage-driven frequency modulation of SHNOs facilitates the development of energy-efficient spin-based neuromorphic devices.
References:
1 J.-G. Choi, et al. Nat. Commun. accepted for publication