Sub-ns magnetization switching and rf emission in CoFe/Cu/CoFe pillars using spin-transfer effect

Detailed sub-ns, current-induced magnetic switching experiments were performed on pillar-shaped (section 150×85 nm²) trilayers of composition [Co-Fe25(2.5 nm)/Cu(6 nm)/Co-Fe25(40 nm)] in the temperature range 50 K to 300 K. The switching speed was correlated with the spin transfer-induced microwave emission occurring just below the switching threshold. All experiments were made in zero applied-field. The switching speed was investigated with current pulses of durations from 100 ps to dc. Quasi-static loops indicate that the reversal events imply transition states with reduced remanences.