Thermally induced rotons in two-dimensional dilute Bose gases
Abstract
We show that roton-like excitations are thermally induced in a two-dimensional dilute Bose gas as a consequence of the strong phase fluctuations in two dimensions. At low momentum, the roton-like excitations lead for small enough temperatures to an anomalous phonon spectrum with a temperature dependent exponent reminiscent of the Kosterlitz-Thouless transition. Despite the anomalous form of the energy spectrum, it is shown that the corresponding effective theory of vortices describes the usual Kosterlitz-Thouless transition. The possible existence of an anomalous normal state in a small temperature interval is also discussed.
Cite
@article{arxiv.cond-mat/0503523,
title = {Thermally induced rotons in two-dimensional dilute Bose gases},
author = {Flavio S. Nogueira and Hagen Kleinert},
journal= {arXiv preprint arXiv:cond-mat/0503523},
year = {2007}
}
Comments
21 pages; 2 figures; v4: version accepted for publication in PRB; in this version Section IV is considerably extended