Charge transport and phase transition in exciton rings
Abstract
The macroscopic exciton rings observed in the photoluminescence (PL) patterns of excitons in coupled quantum wells (CQWs) are explained by a series of experiments and a theory based on the idea of carrier imbalance, transport and recombination. The rings are found to be a source of cold excitons with temperature close to that of the lattice. We explored states of excitons in the ring over a range of temperatures down to 380 mK. These studies reveal a sharp, albeit continuous, second order phase transition to a low-temperature ordered exciton state, characterized by ring fragmentation into a periodic array of aggregates. An instability at the onset of degeneracy in the cold exciton system, due to stimulated exciton formation, is proposed as the transition mechanism.
Cite
@article{arxiv.cond-mat/0308117,
title = {Charge transport and phase transition in exciton rings},
author = {L. V. Butov and L. S. Levitov and A. V. Mintsev and B. D. Simons and A. C. Gossard and D. S. Chemla},
journal= {arXiv preprint arXiv:cond-mat/0308117},
year = {2008}
}
Comments
8 pages including 4 figures