Independent Control of Antiparallel-and Parallel-State Thermal Stability Factors in Magnetic Tunnel Junctions for Telegraphic Signals with Two Degrees of Tunability

Brandon R. Zink, Yang Lv, Jian Ping Wang

Research output: Contribution to journalArticlepeer-review

Abstract

Magnetic tunnel junctions (MTJs) with low thermal stability at room temperature have been proposed as read units in beyond CMOS computing architectures including stochastic computing unit and probabilistic-bit (p-bit). Networks of multiple interconnected MTJs may face challenges due to potential device-to-device variations in thermal stability from design targets. Recently, we generated tunable telegraphic signals using a thermally stable MTJ through proper control over an external bias field and a dc voltage bias, where we showed that the average dwell times in the antiparallel (AP) and parallel states could be tuned separately. The implication for this method for p-bit designs is that it allows for p-bits to be compatible with the state-of-the-art magnetoresistive random-access memory (MRAM) technology and introduces a second degree of tunability to the input-output characteristics of the device. In this article, we expand on this method in two important ways. First, we demonstrate the applicability of our method to p-bit designs by modeling the transfer function using the existing p-bit models. Our results indicate that the transfer function can be adjusted with slight modifications to the bias field, which allows for the possibility of p-bit circuits capable of on-chip corrections against device-to-device variations in their thermal stabilities. Second, we identify the physical mechanisms that allow for two degrees of tunability in the output signal, which is explained through the Néel-Brown model. This article provides both applicability and predictability to the dual-biasing method.

Original languageEnglish (US)
Article number8894522
Pages (from-to)5353-5359
Number of pages7
JournalIEEE Transactions on Electron Devices
Volume66
Issue number12
DOIs
StatePublished - Dec 2019

Keywords

  • Dwell time
  • magnetic tunnel junction (MTJ)
  • p-bit
  • probabilistic computing
  • stochastic computing
  • telegraphic switching
  • tunable randomness

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