Possibility of introducing spin into attoscience with spin-polarized electrons produced by a bichromatic circularly polarized laser field

We show that the electrons, produced in strong-bicircular-field-induced above-threshold ionization of inert-gas atoms, have a large spin asymmetry if the ions exhibit fine-structure splitting. For a bicircular field, which consists of two coplanar counterrotating circularly polarized fields of frequencies $\ensuremath{\omega}$ and $2\ensuremath{\omega}$, the spin-asymmetry parameter changes rapidly with the electron energy. Since the electron--parent-ion rescattering in a counterrotating bicircular field is characterized on the attosecond time scale, this spin asymmetry may introduce the spin degree of freedom into attoscience. We show that the high-energy backward and low-energy forward scattered electrons, which are produced on the scale of a fraction of the laser cycle, exhibit spin asymmetry.