Current-driven microwave oscillations in current perpendicular-to-plane   spin-valve nanopillars
  We study the current and temperature dependences of the microwave voltage emission of spin-valve nanopillars subjected to an in-plane magnetic field and a perpendicular-to-plane current. Despite the complex multilayer geometry, clear microwave emission is shown to be possible and spectral lines as narrow as 3.8 MHz (at 150 K) are observed. 
Q. Mistral, Joo-Von Kim, T. Devolder, P. Crozat, C. Chappert, J. A.   Katine, M. J. Carey, and K. Ito