Electrostatic Langmuir waves and spin-electron-acoustic waves in spin polarized plasma double layer

Abstract

The quantum hydrodynamic model for the electrostatic wave in the two parallel layers of two dimensional electron gases is developed. It is considered for two regimes: classic regime and quantum regime with the separate spin evolution. There are two Langmuir-like waves in the classic regime. Their frequency (ω) dependencies have an interferencelike pattern on concentrations ω2∼(n01+n02 ± 2n01n02), where 01 and n02 are the equilibrium concentrations of the electrons in each layer of electron gas and ± refers to the spectrum of two waves. This spectrum appears instead of the couple of Langmuir waves in two noninteracting two-dimensional electron gases. In the quantum regime, the separate spin evolution leads to the spectrum of four waves instead of the two Langmuir waves present in two noninteracting two-dimensional electron gases. Two extra waves are related to the separate spin evolution of electrons. They are associated with the spin-electron acoustic waves. The contribution of the quantum Bohm potential has also been considered. The influence of the concentrations of electrons, the interlayer distance, and the spin polarization on the spectrum of waves is studied numerically.