Large-angle, gigahertz-rate random telegraph switching induced by   spin-momentum transfer
  We show that spin-polarized dc current passing through a small magnetic element induces two-state, random telegraph switching of the magnetization via the spin-momentum transfer effect. The resistances of the states differ by up to 50% of the change due to complete magnetization reversal. Fluctuations are seen for a wide range of currents and magnetic fields, with rates that can exceed 2 GHz, and involve collective motion of a large volume (10^4 nm^3) of spins. Switching rate trends with field and current indicate that increasing temperature alone cannot explain the dynamics. The rates approach a stochastic regime wherein dynamics are governed by both precessional motion and thermal perturbations. 
Matthew R. Pufall (1), William H. Rippard (1), Shehzaad Kaka (1),   Steven E. Russek (1), Thomas J. Silva (1), Jordan Katine...