Bloch oscillations in the presence of plasmons and phonons

The coupling between Bloch oscillating electrons and longitudinal optical p honons in a superlattice leads to resonant phonon excitation but no gap in the Bloch-phonon spectrum. In addition. we predict a sharp transition from plasma to Bloch oscillations at v(B) = 2v(p). From a microscopic descriptio n with phenomenological dampings, we numerically map out the behavior of co upled Bloch-plasmon-phonon modes for a wide range of parameters, and mimic experimental conditions. Our results are in good agreement with recent expe riments by Dekorsy et al. [Phys. Rev. Lett. 85, 1080 (2000).