  We demonstrate ultra-fast (down to 400 ps) bipolar magnetization switching of
a three-terminal perpendicular Ta/FeCoB/MgO/FeCoB magnetic tunnel junction. The
critical current density rises significantly as the current pulse shortens
below 10 ns, which translates into a minimum in the write energy in the ns
range. Our results show that SOT-MRAM allows fast and low power write
operations, which renders it promising for non-volatile cache memory
applications.
