We report on microwave oscillations induced by spin-transfer-torque in metallic spin-valves obtained by electrodeposition
of Co-Cu-Co trilayer structures in nanoporous alumina templates. Using micromagnetic calculations
performed on similar spin-valve structures it was possible to identify the magnetization dynamics associated
with the experimentally determined microwave emission. Furthermore 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 spin-valve structures. Microwave emission was obtained in the absence of any external
magnetic field with the appropriate magnetization configuration.