  We propose the use of resonant tunneling as a route to enhance the
spin-transfer torque switching characteristics of magnetic tunnel junctions.
The proposed device structure is a resonant tunneling magnetic tunnel junction
based on a MgO-semiconductor heterostructure sandwiched between a fixed magnet
and a free magnet. Using the non-equilibrium Green's function formalism coupled
self consistently with the Landau-Lifshitz-Gilbert-Slonczewski equation, we
demonstrate enhanced tunnel magneto-resistance characteristics as well as lower
switching voltages in comparison with traditional trilayer devices. Two device
designs based on MgO based heterostructures are presented, where the physics of
resonant tunneling leads to an enhanced spin transfer torque thereby reducing
the critical switching voltage by up to 44%. It is envisioned that the
proof-of-concept presented here may lead to practical device designs via
rigorous materials and interface studies.
