  We investigate the charge and spin transport of a voltage-biased
superconducting point contact coupled to a nanomagnet. The magnetization of the
nanomagnet is assumed to precess with the Larmor frequency, $\omega_L$, due to
ferromagnetic resonance. The interplay between the ac Josephson current and the
magnetization dynamics leads to spin-polarized Shapiro steps at voltages
$|V|=\hbar \omega_L/2en$ for $n=1,2,...$ and the subharmonic steps with $n>1$
are a consequence of multiple Andreev reflection (MAR). Moreover, the
spin-precession-assisted MAR generates quasiparticle scattering amplitudes
that, due to interference, lead to current-voltage characteristics of the dc
charge and spin currents with subharmonic gap structures displaying an even-odd
effect.
