Quartic Lattice Interactions, Soliton-like Excitations and Electron Pairing in One-Dimensional Anharmonic Crystals

TL;DR

This paper demonstrates that in one-dimensional anharmonic lattices, excess electrons can form stable, bound pairs called bisolectrons, which are localized with soliton-like lattice deformations, even considering Coulomb repulsion.

Contribution

It introduces the concept of bisolectrons in anharmonic lattices and analyzes their stability and energy properties including Coulomb effects.

Findings

Bisolectrons form as bound states of electron pairs with lattice deformations.

Bisolectron wave functions have two maxima when Coulomb repulsion is included.

Bisolectron energy is lower than that of two independent electrons, indicating stable pairing.

Abstract

We show that two added, excess electrons with opposite spins in one-dimensional crystal lattices with quartic anharmonicity may form a bisolectron, which is a localized bound state of the paired electrons to a soliton-like lattice deformation. It is also shown that when the Coulomb repulsion is included, the wave function of the bisolectron has two maxima, and such a state is stable in lattices with strong enough electron-(phonon/soliton) lattice coupling. Furthermore the energy of the bisolectron is shown to be lower than the energy of the state with two separate, independent electrons, as even with account of the Coulomb repulsion the bisolectron binding energy is positive