Micromagnetic simulations of linewidth and nonlinear frequency shift coefficient in spin-torque nanoscillators

The dependence of the linewidth on the temperature and the applied magnetic field angle is studied in spin torque nano-oscillators (STNO) by means of full micromagnetic simulations. Linewidth behavior increases with the temperature in agreement with the analytical predictions by Tiberkevic et al. [Phys. Rev. B, 78, 092401 (2008)] and its slope depends on the applied field angle. Also, the nonlinear frequency shift coefficient, which gives a measure of the nonlinearity degree of STNO and indicates the strength of the transformation of amplitude into phase fluctuations, is found.