Phenomenological approach to the two-stream instability in two parallel two-dimensional metals

Phenomenologic description of the two-stream instability in two parallel two-dimensional (2D) metals is derived. The frequency and rate of growth of an instable mode is expressed in terms of frequencies and damping of plasma waves in isolated 2D metals. These input parameters are experimentally accessible, e.g., by the far-infrared spectroscopy or by the Raman scattering. The presented theory indicates that a system with one metal driven and the second one kept under the zero current condition is more promising for the instability than two metals driven in the opposite directions.