We predict a possible phonon softening instability in strongly correlated coupled semiconductor bilayer systems. By studying the plasmon-phonon coupling in coupled bilayer structures, we find that the renormalized acoustic phonon frequency may be softened at a finite wave vector due to many-body local field corrections, particularly in low density systems where correlation effects are strong. We discuss experimental possibilities to search for this predicted phonon softening phenomenon.
@article{arxiv.cond-mat/0012482,
title = {Correlation induced phonon softening in low density coupled bilayer systems},
author = {E. H. Hwang and S. Das Sarma},
journal= {arXiv preprint arXiv:cond-mat/0012482},
year = {2009}
}