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 journalArticle

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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