  We explore spin-torque induced magnetic reversal in magnetic tunnel junctions
using combined AC and DC spin-current pulses. We calculate the optimal pulse
times and current strengths for both AC and DC pulses as well as the optimal AC
signal frequency, needed to minimize the Joule heat lost during the switching
process. The results of this optimization are compared against numeric
simulations. Finally we show how this optimization leads to different dynamic
regimes, where switching is optimized by either a purely AC or DC spin-current,
or a combination AC/DC spin-current, depending on the anisotropy energies and
the spin-current polarization.
