Superlight bipolarons and criterion of BCS-BEC crossover in cuprates
Abstract
Most of the proposed models of high-temperature superconductivity (HTSC) are based on the short-range electron-electron correlations or/and on a short-range electron-phonon interaction. However, in the cuprates the screening is poor due to a low carrier density, layered crystal structure, and high ionicity of the lattice. We develop further the bipolaron model of HTSC, which explicitly takes into account the long-range origin of all interactions. The long-range electron-phonon (Froehlich) interaction binds carriers into real space pairs (small bipolarons) with surprisingly low mass but sufficient binding energy, while the long-range Coulomb repulsion keeps them from forming larger clusters. The model has explained many key features of cuprates. Here it is shown that real-space pairing takes place in many cuprates at variance with some (incorrect) criteria of the BCS-BEC crossover.
Keywords
Cite
@article{arxiv.cond-mat/0301541,
title = {Superlight bipolarons and criterion of BCS-BEC crossover in cuprates},
author = {A. S. Alexandrov},
journal= {arXiv preprint arXiv:cond-mat/0301541},
year = {2015}
}
Comments
2 pages, 1 figure, invited paper at the New3SC-4 Conference (San Diego, CA, January 2003)