Comment on `Experimental and Theoretical Constraints of Bipolaronic Superconductivity in High $T_{c}$ Materials: An Impossibility'

TL;DR

This paper refutes previous objections to the bipolaron model of high-temperature superconductivity, demonstrating that cuprates can indeed be described as Bose-Einstein condensates of mobile bipolarons when considering multiband effects and unscreened interactions.

Contribution

It corrects earlier misconceptions by incorporating multiband structures and unscreened electron-phonon interactions into bipolaron theory, supporting the viability of bipolaronic superconductivity in cuprates.

Findings

Cuprates are in the Bose-Einstein condensation regime with mobile bipolarons.

Previous objections were based on incorrect approximations of bipolaron energy spectrum.

Multiband effects and unscreened interactions support bipolaronic superconductivity.

Abstract

We show that objections raised by Chakraverty $et$ $al$ (Phys. Rev. Lett. 81, 433 (1998)) to the bipolaron model of superconducting cuprates are the result of an incorrect approximation for the bipolaron energy spectrum and misuse of the bipolaron theory. The consideration, which takes into account the multiband energy structure of bipolarons and the unscreened electron-phonon interaction clearly indicates that cuprates are in the Bose-Einstein condensation regime with mobile charged bosons.