Recent progress in random number generator using voltage pulse-induced switching of nano-magnet: A perspective

Voltage pulse-driven switching of nano-magnets has gained distinct attention because of its high-speed writing with ultralow power consumption. One of the key advantages is that the external voltage applied to a nano-magnet reduces the magnetic anisotropy energy and excites a precessional motion of magnetization. By adjusting the duration and amplitude of the voltage pulse, a switching probability close to 50% can be attained, suggesting that the magnetic state of nano-magnets can be used as a source for generating binary random numbers (RNs) in principle. Because the bi-directional switching of nano-magnets is induced by unipolar voltage pulses, which is essentially different from the case of spin transfer torque (STT) switching, the results are a mixture of two switching polarities: from parallel (“0” state) to antiparallel (“1” state) and vice versa. Here, we focus our attention on the appearance probabilities of four cases, “00,” “01,” “10,” and “11,” all of which change linearly as functions of voltage. By tuning the probabilities of “00” or “11” to 25%, well-balanced RNs can be generated. A clear advantage of the voltage-pulse driven random number generator (RNG) over the conventional STT-driven one is lower consumption, which enables integration and heavily parallel operations of a large number of RNGs.