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

Area of Science:

• Physics
• Materials Science
• Computer Engineering

Background:

• Superparamagnetic tunnel junctions (SMTJs) offer a source of randomness crucial for compact and energy-efficient computing.
• Collective behavior in coupled SMTJs holds potential for advanced cognitive computing architectures.

Purpose of the Study:

• To investigate the effects of mutual electrical coupling on the stochastic transitions of two SMTJs.
• To explore the emergence of correlated behavior in coupled SMTJ systems.

Main Methods:

• Two SMTJs were mutually coupled using a linear electrical circuit.
• The stochastic electrical transitions of individual SMTJs were modeled using a generalized Néel-Brown model.
• The behavior of the coupled SMTJ system was analyzed using a Markov model.

Main Results:

• Mutual electrical coupling significantly induced correlations between the states of the two SMTJs.
• The voltage changes from one SMTJ's transition influenced the transition rates of the other.
• The generalized Néel-Brown model fits accurately predicted the coupled devices' behavior.

Conclusions:

• Coupling SMTJs via a simple electrical circuit effectively generates correlated stochastic behavior.
• This correlated behavior is accurately reproducible using Markov modeling.
• The findings support the use of coupled SMTJs for randomness generation in cognitive computing systems.