  The unique resonance and locking phenomena in the
superconductor-ferromagnet-superconductor $\varphi_0$ Josephson junction under
external electromagnetic radiation are demonstrated when not just the electric
but also the magnetic component of external radiation is taken into account.
Due to the coupling of superconductivity and magnetism in this system, the
magnetic moment precession of the ferromagnetic layer caused by the magnetic
component of external radiation can lock the Josephson oscillations, which
results in the appearance of a particular type of steps in the current-voltage
characteristics, completely different from the well-known Shapiro steps. We
call these steps the Buzdin steps in the case when the system is driven only by
the magnetic component and the Chimera steps in the case when both magnetic and
electric components are present. Unlike the Shapiro steps where the
magnetization remains constant along the step, here it changes though the
system is locked. The spin-orbit coupling substantially contributes to the
amplitude, i.e., the size of these steps. Dramatic changes in their amplitudes
are also observed at frequencies near the ferromagnetic resonance. Combinations
of the Josephson and Kittel ferromagnetic resonances together with different
types of locking pronounced in dynamics and current-voltage characteristics
make the physics of this system very interesting and open up a series of new
applications.
