A team of researchers from Bielefeld and Berlin, together with researchers from other research institutes in Germany and Spain, recently demonstrated that graphene's nonlinearity can be efficiently controlled by applying comparatively modest electrical voltages to the material.
The gated graphene sample device in which the graphene film acts as a channel between source and drain electrodes subjected to a constant potential difference of 0.2 mV. Image from Science Advances
It was recently discovered that the high electronic conductivity and "massless" behavior of graphene's electrons allows it to alter the frequency components of electric currents that pass through it. This property is highly dependent on how strong this current is. In modern electronics, such a nonlinearity comprises one of the most basic functionalities for switching and processing of electrical signals. What makes graphene unique is that its nonlinearity is by far the strongest of all electronic materials. Moreover, it works very well for exceptionally high electronic frequencies, extending into the technologically important terahertz (THz) range where most conventional electronic materials fail.