Effects of phonon dispersion on bond-bipolaron superconductivity

Chao Zhang; Nikolay Prokof'ev; Boris Svistunov

doi:10.1103/PhysRevB.111.184513

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Effects of phonon dispersion on bond-bipolaron superconductivity

Chao Zhang, Nikolay Prokof'ev, Boris Svistunov

DOI 10.1103/PhysRevB.111.184513 · Physical Review B

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Abstract

We employ the diagrammatic Monte Carlo method based on lattice path-integral representation of the particle sector and real-space diagrammatics of the phonon sector to study the effects of optical phonon dispersion on Bose-Einstein condensation of bipolarons in the bond model. For dispersionless phonons with frequency ω, this model was recently shown to give rise to small-size, light-mass bipolarons that undergo a superfluid transition at high values of the Tc/ω ratio. We find that for dispersive phonons, Tc remains relatively high over a broader range of the coupling strength and even keeps increasing in the deep adiabatic regime both in two and three dimensions. This result implies that phonon dispersion is not a limiting factor in the search for new materials with high superconducting temperatures.