Superparamagnetic perpendicular magnetic tunnel junctions for true random number generators

Bradley Parks,Weigang Wang,Sara A Majetich,Hamid Almasi,Julianne Igbokwe,Mukund Bapna

doi:10.1063/1.5006422

Bradley Parks, Weigang Wang + Show 4 more

Open Access

https://doi.org/10.1063/1.5006422

Copy DOI

Journal: AIP Advances	Publication Date: Dec 7, 2017
Citations: 48	License type: cc-by

Affiliation: Carnegie Mellon University, University of Arizona

Abstract

Superparamagnetic perpendicular magnetic tunnel junctions are fabricated and analyzed for use in random number generators. Time-resolved resistance measurements are used as streams of bits in statistical tests for randomness. Voltage control of the thermal stability enables tuning the average speed of random bit generation up to 70 kHz in a 60 nm diameter device. In its most efficient operating mode, the device generates random bits at an energy cost of 600 fJ/bit. A narrow range of magnetic field tunes the probability of a given state from 0 to 1, offering a means of probabilistic computing.

Highlights

Encryption is vital to protecting everything from personal data to financial transactions to national security information., and recent high profile compromises of data security highlight the need for better encryption
We present experimental results from a 60nm hardwired SP-perpendicular MTJs (pMTJs) used as a true random number generator with voltage tunable frequency
Driven magnetization reversal of a superparamagnet is described by a Neel relaxation model, with a relaxation time given by τ = τ0 exp[Keff V/kBT], where τ is the average time spent in the state, τ0 is the inverse of the Larmor precession frequency, Keff is the effective anisotropy, V is the volume, kB is the Boltzmann constant, and T is the temperature

Summary

Introduction

Encryption is vital to protecting everything from personal data to financial transactions to national security information., and recent high profile compromises of data security highlight the need for better encryption Due to their limited speed, large area, and high power consumption, it is not feasible to generate true random numbers fast enough for real-time encryption, hardware random number generators (RNGs) are used to seed pseudo-random number generating algorithms. The variability of the frequencies in the ring oscillator and clock give rise to a random walk in their relative phase, with the frequency of each component being dependent on the temperature These circuits are typically hundreds of square microns, consume milliwatts of power, and generate tens to hundreds of megabits per second.[2] Recent experiments in CMOS based RNGs have increased the speed to a few gigabits per second and reduced area by a factor of ten, but without significant reduction in power consumption.[3]

Methods

Results

Conclusion