  We study interlayer exchange coupling (IEC) based on the many-body Coulomb
interaction between conduction electrons in magnetic tunnel junction (MTJ).
This mechanism complements the known IEC based on virtual electron hopping (or
spin currents). We find that these two mechanisms have different behavior on
system parameters. The Coulomb based IEC may exceed the hopping based exchange
coupling. We show that the Coulomb based exchange coupling, in contrast to the
hopping based coupling, depends strongly on the dielectric constant of the
insulating layer. The dependence of the IEC on the dielectric properties of the
insulating layer in MTJ is similar to magneto-electric (ME) effect where
electric and magnetic degrees of freedom are coupled. We calculate the IEC as a
function of temperature and electric field for MTJ with ferroelectric (FE)
layer and show that IEC has a sharp decrease in the vicinity of the FE phase
transition and varies strongly with external electric field.
