Electrical coupling of superparamagnetic tunnel junctions mediated by spin-transfer-torques

TL;DR

This paper investigates how electrical coupling mediated by spin-transfer-torques influences the stochastic switching behavior of superparamagnetic tunnel junctions, demonstrating voltage-controlled coupling strength and direction through experiments and simulations.

Contribution

It introduces a detailed study of voltage-tunable electrical coupling in SMTJs mediated by spin-transfer-torques, combining experimental measurements with simulations.

Findings

Strong coupling at high positive voltages

Coupling strength and direction are voltage-dependent

Experimental results agree with simulations

Abstract

In this work, the effect of electrical coupling on stochastic switching of two in-plane superparamagnetic tunnel junctions (SMTJs) is studied, using experimental measurements as well as simulations. The coupling mechanism relies on the spin-transfer-torque (STT) effect, which enables the manipulation of the state probability of an SMTJ. Through the investigation of time-lagged cross-correlation, the strength and direction of the coupling are determined. In particular, the characteristic state probability transfer curve of each SMTJ leads to the emergence of a similarity or dissimilarity effect. The cross-correlation as a function of applied source voltage reveals that the strongest coupling occurs for high positive voltages for our SMTJs. In addition, we show state tuneability as well as coupling control by the applied voltage. The experimental findings of the cross-correlation are in agreement with our simulation results.