Negative conductivity and anomalous screening in two-dimensional electron systems subjected to microwave radiation

Abstract

A 2D electron system in a quantized magnetic field can be driven by microwave radiation into a non-equilibrium state with strong magnetooscillations of the dissipative conductivity. We demonstrate that in such system a negative conductivity can coexist with a positive diffusion coefficient. In a finite system, solution of coupled electrostatic and linear transport problems shows that the diffusion can stabilize a state with negative conductivity. Specifically, this happens when the system size is smaller than the absolute value of the non-equilibrium screening length that diverges at the point where the conductivity changes sign. We predict that a negative resistance can be measured in such a state. Further, for a non-zero difference between the work functions of two contacts, we explore the distribution of the electrostatic potential and of the electron density in the sample. We show that in the diffusion-stabilized regime of negative conductivity the system splits into two regions with opposite directions of electric field. This effect is a precursor of the domain structure that has been predicted to emerge spontaneously in the microwave-induced zero-resistance states.

8 pages, 4 figures

References in corpus (6)

• Theory of microwave-induced oscillations in the magnetoconductivity of a 2D electron gas
• Observation of Apparently Zero-Conductance States in Corbino Samples
• Mechanisms of the microwave photoconductivity in 2D electron systems with mixed disorder
• Are Microwave Induced Zero Resistance States Necessarily Static?
• Photo-current and photo-voltage oscillations in the two-dimensional electron system: screening and "anti-screening" of a potential profile
• Theory of the microwave-induced photocurrent and photovoltage magnetooscillations in a spatially non-uniform 2D electron gas

Cited by in corpus (4)

• Nonequilibrium phenomena in high Landau levels
• Observation of terahertz-induced magnetooscillations in graphene
• Microwave-Induced Oscillations in the Magnetocapacitance: Direct Evidence for Non-equilibrium Occupation of Electronic States
• Emergence of domains and nonlinear transport in the zero-resistance state