Random numbers are essential in many information technologies, especially those concerning cyber security. Nowadays, most random numbers are the pseudo random numbers generated by mathematical algorithms. A compact, fast, and true random number generator (TRNG) is highly desirable.
Left: A dice is a random nubmer generator. Right: A MTJ memory element becomes a TRNG when the fluctaution of the free layer magnetization becomes fast.
It has been proposed that a TRNG can be constructed from a magnetic tunnel junction (MTJ), utilizing the thermal activated random magnetization switching. However, the MTJ-based TRNG can only operate at a relatively low frequency of 1KHz. Many efforts have been tried to enhance its generation rate.
In our recent paper [1], we demonstrate theoretically and confirmed by simulation that an application of a millitesla magnetic field can significantly reduce the potential barrier between the two equilibrium states, therefore enhance the random number generation rate of an MTJ-based TRNG by many orders of magnitude, from KHz to GHz. More importantly, the applied field has little effect on the read-out of the random numbers in the MTJ.
This paper provides a simple yet effective method in enabling MTJ as a fast true random number generator. And the physical realization of this method can turn the MTJ-based TRNG into a commercially competitive device in many applications based on random numbers.
This work was mainly conducted by Mr. Xiheng Chen, who just finished his Master study in Fudan University and moved on to industry.
Reference:
[1]. Magnetic-Tunnel-Junction-Based True Random-Number Generator with Enhanced Generation Rate
Xiheng Chen, Jiabing Zhang, and Jiang Xiao*
Phys. Rev. Applied 18, L021002 (2022).