  The non-autonomous dynamics of spin-torque oscillators in presence of both
microwave current and field at the same frequency can exhibit complex
non-isochronous effects. A non-stationary mode hopping between quasi-periodic
mode (frequency pulling) and periodic mode (phase locking), and a deterministic
phase slip characterized by an oscillatory synchronization transient
(non-Adlerian phase slip) after the phase jump of have been predicted. In the
latter effect, a wavelet based analysis reveals that in the positive and
negative phase jump the synchronization transient occurs at the frequency of
the higher and lower sideband frequency respectively. The non-Adlerian phase
slip effect, even if discovered in STOs, is a general property of
non-autonomous behavior valid to any non-isochronous auto-oscillator in regime
of moderate and large force locking.
