Temperature dependence of spin-torque-driven self-oscillations

We have measured the temperature dependence of spin-torque-driven self-oscillations in point-contact nano-oscillators for both in-plane and out-of-plane applied fields. We find that the linewidth for both field geometries is qualitatively similar. In the absence of observable low-frequency noise, at high temperatures the linewidth decreases roughly linearly as the temperature decreases. However, extrapolation of the quasilinear region to a zero-temperature linewidth intercept can yield either a positive or negative value. This variation in the zero-temperature linewidth intercept indicates that a range of mechanisms must be involved in setting the linewidth. When $1/f$ noise is present in the device power spectrum, the linewidth varies quasiexponentially with temperature. While the linewidth versus temperature behavior is similar for both in-plane and out-of-plane applied fields, their output power versus current variation with temperature is qualitatively different.