Hydrodynamical study of terahertz emission in magnetized graphene field-effect transistors

Abstract

Several hydrodynamic descriptions of charge transport in graphene have been presented in recent years. We discuss a general hydrodynamic model governing the dynamics of a two-dimensional electron gas in a magnetized field-effect transistor in the slow drift regime. The Dyakonov-Shur instability is investigated, including the effect of weak magnetic fields (i.e., away from Landau levels). We verify that the occurrence of the gap on the dispersion relation imposes a limit on the Mach number of the electronic flow, as it does not allow the unstable frequencies to be below ωc. Furthermore, we discuss that the presence of the external magnetic field decreases the growth rate of the instability, as well as the saturation amplitude. The numerical results from our simulations and the presented higher order dynamic mode decomposition support such reasoning.