Coherent control of nanomagnet dynamics via ultrafast spin torque pulses

We demonstrate reliable manipulation of the magnetization dynamics of a precessing nanomagnet by precisely controlling the spin transfer torque on the subnanosecond time scale. Using a simple pulse shaping scheme consisting of two ultrafast spin torque pulses with variable amplitudes and delay, we demonstrate coherent control over the precessional orbits and the ability to tune the switching probability of a nanomagnet at room temperature and 77 K. Our measurements suggest that appropriately shaped spin transfer can be used to efficiently manipulate the orientation of a free layer nanomagnet, thus providing an alternative for spin torque driven spintronic devices.