Narrow spectral lines in spin-transfer oscillators based on spin-valve nanopillars

We demonstrate that microwave oscillations with linewidths as narrow as 3.2 MHz are possible in spin-valve nanopillars. This is remarkable because comparable linewidths have so far only been observed in point-contact geometries .in which self-localization of magnetization oscillations is argued to be responsible for narrow spectral lines. Furthermore, our system is a complete spin-valve stack comprising a complex multilayer structure, which suggests that high quality-factor oscillations are a universal feature of spin-momentum transfer and are not restricted to model geometries.