Orientation dependence of residual current in graphene by few-cycle linearly polarized light

The orientation dependence of residual current in graphene is investigated using linearly polarized light. We find that the measured residual currents have unexplored oscillation-like small modulation in addition to the main modulation. In order to clarify the origin of this small modulation, the residual current is decomposed into two components, parallel and perpendicular to the laser polarization direction. The parallel current component’s variation with orientation is influenced by the transition dipole moment, however, that of the perpendicular current component is dominated by the group velocity in the perpendicular direction, which is the main origin of small modulation. These results demonstrate a strong link between graphene band structure and residual current, which is expected to provide some insights into the development of petahertz light-field information technology.