Predicted DC current induced by propagating wave in gapless Dirac materials

In this paper, we show that the application of propagating waves can induce a DC current even in systems with spatial inversion symmetry. We derive the equation for the DC current induced by propagating waves using two methods: perturbation theory and Floquet theory. These two approaches yield consistent results. We then apply the equation to gapless graphene subjected to propagating waves. A nonzero DC current is predicted in graphene with next nearest neighbor hopping terms. Nonperturbative effects arising from a strong wave amplitude are also discussed within the framework of Floquet theory.