  We propose an electric-field-controlled mechanism for magnetization switching
assisted solely by the interlayer-exchange coupling (IEC) between the fixed and
the free magnets, which are separated by two oxide barriers sandwiching a
spacer material known for exhibiting large IEC. The basic idea relies on the
formation of a quantum-well (QW) within the spacer material and controlling the
transmission coefficient across the structure with an electric-field via the
resonant tunneling phenomena. Using non-equilibrium Green's function (NEGF)
method, we show that the structure can exhibit a bias-dependent oscillatory IEC
that can switch the free magnet to have either a parallel or an antiparallel
configuration with respect to the fixed magnet, depending on the sign of the
IEC. Such bi-directional switching can be achieved with the same voltage
polarity but different magnitudes. With proper choice of the spacer material,
the current in the structure can be significantly reduced. Due to the
conservative nature of the exerted torque by the IEC, the switching threshold
of the proposed mechanism is decoupled from the switching speed, while the
conventional spin-torque devices exhibit a trade-off due to the
non-conservative nature of the exerted torque.
