Dielectric matrix and plasmon dispersion in strongly coupled electronic bilayer liquids

Collective excitations in electron-hole bilayers

We report a combined analytic and molecular dynamics analysis of the collective mode spectrum of a bipolar (electron-hole) bilayer in the strong coupling classical limit. A robust, isotropic energy gap is identified in the out-of-phase spectra, generated by the combined effect of correlations and of the excitation of the bound dipoles. In the in-phase spectra we identify longitudinal and transverse acoustic modes wholly maintained by correlations. Strong nonlinear generation of higher harmonics of the fundamental dipole oscillation frequency and the transfer of harmonics between different modes is observed.

Transverse dielectric matrix and shear mode dispersion in strongly coupled electronic bilayer liquids

The authors develop a transverse dielectric matrix and from it they calculate the shear mode dispersion in strongly coupled charged-particle bilayer liquids in the T=0 quantum domain. The formulation is based on the classical quasilocalized charge approximation (QLCA) and extends the QLCA formalism into the quantum domain. Its development parallels and complements the development of a similarly extended longitudinal dielectric matrix formalism reported in a recent companion work [K. I. Golden, H. Mahassen, G. J. Kalman, G. Senatore, and F. Rapisarda, Phys. Rev. E 71, 036401 (2005)]. Using pair correlation function data generated from diffusion Monte Carlo simulations, the authors calculate the dispersion of the in-phase and out-of-phase shear modes over a wide range of high-r(s) values and layer separations. Over the coupling range 10< or =r(s)< or =30 and for layer separations 0.2/sqrt[pi(n)]< or =d< or =0.5/sqrt[pi(n)] , the present study predicts the existence of a robust out-of-phase gapped shear mode dispersion in the domain of the q,omega -plane above the left boundary of the RPA single-pair excitation region; under these conditions, the out-of-phase collective excitation is entirely immune to Landau damping and can be safely considered to be mostly unaffected by diffusive-migrational damping.