  Spin-polarization effects of an ultrarelativistic electron beam head-on
colliding with an ultraintense two-color laser pulse are investigated
comprehensively in the quantum radiation-dominated regime. We employ a Monte
Carlo method, derived from the recent work of [Phys. Rev. Lett. {\bf 122},
154801 (2019)], to calculate the spin-resolved electron dynamics and photon
emissions in the local constant field approximation. We find that electron
radiation probabilities in adjacent half cycles of a two-color laser field are
substantially asymmetric due to the asymmetric field strengths, and
consequently, after interaction the electron beam can obtain a total
polarization of about 11\% and a partial polarization of up to about 63\%
because of radiative spin effects, with currently achievable laser facilities,
which may be utilized in high-energy physics and nuclear physics. Moreover, the
considered effects are shown to be crucially determined by the relative phase
of the two-color laser field and robust with respect to other laser and
electron beam parameters.
