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arXiv · 1112.3230

Superlight small bipolarons from realistic long-range Coulomb and Fröhlich interactions

A. S. Alexandrov·J. H. Samson·G. Sica
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Abstract

We report analytical and numerical results on the two-particle states of the polaronic t-Jp model derived recently with realistic Coulomb and electron-phonon (Frohlich) interactions in doped polar insulators. Eigenstates and eigenvalues are calculated for two different geometries. Our results show that the ground state is a bipolaronic singlet, made up of two polarons. The bipolaron size increases with increasing ratio of the polaron hopping integral t to the exchange interaction Jp but remains small compared to the system size in the whole range 0<t/Jp<1. Furthermore, the model exhibits a phase transition to a superconducting state with a critical temperature well in excess of 100K. In the range t/Jp<1, there are distinct charge and spin gaps opening in the density of states, specific heat, and magnetic susceptibility well above Tc.

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A. S. Alexandrov, J. H. Samson, G. Sica. 2012-02-02. Superlight small bipolarons from realistic long-range Coulomb and Fröhlich interactions. https://doi.org/10.1103/physrevb.85.104520

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