Microwave phase-locking of several spin-torque nano-oscillators with different eigen parameters

Phase-locking processes in the systems of several weakly-coupled spin-torque nano-oscillators (STNOs) with different eigen parameters are analyzed. It is shown that microwave dynamics of such STNO systems is complicated enough and can be fuzzy, while the system's synchronization state can be well described by a small variation of the modulus of the complex order parameter over time. Using this approach the microwave synchronization of several (two, three and five) STNOs is studied numerically and the optimal values of amplitude and phase of the global coupling are determined.