  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.
