A bottom-up approach for the fabrication of an assembly of electrodeposited nanowires has been combined to single nanowire electrical connection techniques to investigate the spin-transfer-torque and microwave emission of specially designed nanowires containing Co/Cu/Co pseudo spin-valves (SVs). Porous alumina templates are used for the growth by electrodeposition of metallic in-series connected SVs. Under specific magnetic field and injected current conditions, emission of microwave current is detected with frequency in the GHz range and linewidth as low as 1.8[Formula: see text]MHz. Microwave signals have been obtained even at zero magnetic field and high frequency versus magnetic field tunability was demonstrated. Our findings are in good agreement with micromagnetic simulations. In addition, it appears that in our particular geometry, the microwave emission is generated by the vortex gyrotropic motion which occurs in, at least, one of the two magnetic layers of our SV structures.
Comparison between thermal and current driven spin-transfer torque in nanopillar metallic spin valves
