Controlling nondipole effects with bicircular laser fields

We experimentally and theoretically investigate the nondipole shift of the electron momentum distribution in the light-propagation direction in strong-field ionization of Ar atoms using counterrotating circularly polarized two-color laser fields. We observe that the electron mean momentum in the laser propagation direction in bicircular fields is strongly dependent on both the emission angle theta and the radial momentum pr of the electron. In low-energy electrons, the mean momentum follows the relation p2r/2c + Ip/3c (c is the velocity of light and Ip is the ionization potential), while for high-energy electrons it is significantly suppressed and deviates from the predicted values. Using nondipole-corrected classical trajectory Monte Carlo simulations, we identify that the nondipole shift is significantly influenced by the electron scattering process. The dominance of scattered electrons in the high-energy region leads to the reduction of the mean momentum shift. By extracting the angleand momentum-resolved mean momentum spectrum, we show that the scattered and nonscattered electrons are emitted at different angles in counterrotating circularly polarized fields due to the nondipole shift. The sensitivity of the nondipole effect to the scattering process serves as a promising tool for probing strong-field-driven electron dynamics.