Mutual control of stochastic switching for two electrically coupled superparamagnetic tunnel junctions

Philippe Talatchian, Matthew W. Daniels, Advait Madhavan, Matthew R. Pufall, Emilie Jué, William H. Rippard, Jabez J. McClelland, and Mark D. Stiles

Phys. Rev. B 104, 054427 – Published 19 August 2021

Abstract

Superparamagnetic tunnel junctions (SMTJs) are promising sources for the randomness required by some compact and energy-efficient computing schemes. Coupling SMTJs gives rise to collective behavior that could be useful for cognitive computing. We use a simple linear electrical circuit to mutually couple two SMTJs through their stochastic electrical transitions. When one SMTJ makes a thermally induced transition, the voltage across both SMTJs changes, modifying the transition rates of both. This coupling leads to significant correlation between the states of the two devices. Using fits to a generalized Néel-Brown model for the individual thermally bistable magnetic devices, we can accurately reproduce the behavior of the coupled devices with a Markov model.

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Received 7 June 2021
Revised 25 July 2021
Accepted 9 August 2021

DOI:https://doi.org/10.1103/PhysRevB.104.054427

Physics Subject Headings (PhySH)

Fluctuations & noise Stochastic processes Superparamagnetism

Magnetic tunnel junctions

Electrical techniques Markovian processes Monte Carlo methods Sputtering

Condensed Matter, Materials & Applied PhysicsStatistical Physics & Thermodynamics

Authors & Affiliations

Philippe Talatchian ^1,2,3,*, Matthew W. Daniels ^4,†, Advait Madhavan^1,2, Matthew R. Pufall⁵, Emilie Jué^6,7, William H. Rippard⁵, Jabez J. McClelland ⁴, and Mark D. Stiles ^4,‡

¹Associate, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
²Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
³Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
⁴Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
⁵Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 20305, USA
⁶Associate, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 20305, USA
⁷Department of Physics, University of Colorado, Boulder 20309, USA

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Vol. 104, Iss. 5 — 1 August 2021

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