  The temperature dependence of a vortex-based nano-oscillator induced by spin
transfer torque (STVO) in magnetic tunnel junctions (MTJ) is considered. We
obtain emitted signals with large output power and good signal coherence. Due
to the reduced non-linearities compared to the uniform magnetization case, we
first observe a linear decrease of linewidth with decreasing temperature.
However, this expected behavior no longer applies at lower temperature and a
bottom limit of the linewidth is measured.
