Collective electromagnetic excitations in a double-layer two-dimensional electron system in a high magnetic field
- Theoretical Division and the CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
- Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Acad. Proskura St., Kharkov 310085 (Ukraine)
A new type of collective electromagnetic excitations, namely the surface polaritons (SP`s), 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 SP`s 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 SP`s 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 SP`s (ASP`s). 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 mode`s 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)
- OSTI ID:
- 550387
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 56, Issue 16; Other Information: PBD: Oct 1997
- Country of Publication:
- United States
- Language:
- English
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