### Collective electromagnetic excitations in a double-layer two-dimensional electron system in a high magnetic fieldCollective electromagnetic excitations in a double-layer two-dimensional electron system in a high magnetic field

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 Author Aronov, I. E. ♦ Beletskii, N. N. ♦ Berman, G. P. ♦ Bishop, A. R. Source United States Department of Energy Office of Scientific and Technical Information Content type Text Language English
 Subject Keyword PHYSICS ♦ ELECTRON GAS ♦ COLLECTIVE EXCITATIONS ♦ WIGNER DISTRIBUTION ♦ CYCLOTRON RESONANCE ♦ MAGNETIC FIELDS ♦ PHASE VELOCITY ♦ FINE STRUCTURE ♦ DISPERSION RELATIONS ♦ ELECTRON-HOLE COUPLING Abstract A new type of collective electromagnetic excitations, namely the surface polaritons (SPs), in a double-layer two-dimensional electron system (DL2DES) (of nn-type, pp-type, and np-type) in a high magnetic field is predicted. Using a Wigner distribution function formalism, we investigate the spectrum, damping, and polarization of the SPs in a wide range of the frequencies {omega} and the wave vectors {bold k}. It is shown that near the cyclotron resonance (CR) ({omega}{approximately}{Omega}=eB/mc) the phase velocity of the SPs is drastically slowed down, and the group velocity undergoes the fundamental steps defined by the fine-structure constant {alpha}=e{sup 2}/{h_bar}c (as well as for the one-layer 2DES). For the nn-type DL2DES, each dispersion curve splits, and strongly correlated collective electromagnetic excitations propagate in the system. The group velocity of these excitations is defined by the interlayer distance d, and is much smaller than that for the one-layer 2DES. In the vicinity of a CR subharmonic ({omega}{approximately}2{Omega}) the negative (anomalous) dispersion of the SP occurs. For the np-type DL2DES the branches of the dispersion curves are intercrossed in the long-wave region, near the subharmonic (hole) CR, and in the short-wave region, due to the resonance interaction between the principal (electron) CR mode and the subharmonic (hole) CR mode. The relaxation of the electrons (or holes) in the DL2DES leads to the occurrence of a dissipative collective mode of the SP type{emdash}the additional SPs (ASPs). This mode exists under certain threshold condition, which is determined by a fine-structure constant {alpha}. As a consequence, the dispersion curves for these excitations exhibit spectrum endpoints, and modes confluence. The threshold condition for the ASP`s in the DL2DES has a geometrical oscillating form due to the coherence effects between the split ASP modes. (Abstract Truncated) ISSN 01631829 Educational Use Research Learning Resource Type Article Publisher Date 1997-10-01 Publisher Place United States Journal Physical Review, B: Condensed Matter Volume Number 56 Issue Number 16