Bipolarons bound by repulsive phonon-mediated interactions
Abstract
When dressed particles (polarons) exchange quantum phonons, the resulting interactions are generally attractive. If the particles have hard-core statistics and the coupling to phonons is through the kinetic energy terms, phonon-mediated interactions are repulsive. Here, we show that such repulsive phonon-mediated interactions bind dressed particles into bipolarons with unique properties. These bipolaron states appear in the gap between phonon excitations, above the two-polaron continuum. While thermodynamically unstable, the bipolaron is protected by energy and momentum conservation and represents a novel quasiparticle with a large dispersion and a negative effective mass near zero momentum. We discuss possible experimental implementation of the conditions for the formation of such repulsively bound bipolarons.
Cite
@article{arxiv.1708.06826,
title = {Bipolarons bound by repulsive phonon-mediated interactions},
author = {John Sous and Mona Berciu and Roman V. Krems},
journal= {arXiv preprint arXiv:1708.06826},
year = {2018}
}
Comments
7 pages, 4 figures, 2 appendices