The spin-orbit mechanism of electron pairing in quantum wires

TL;DR

This paper demonstrates that image-potential-induced spin-orbit interaction (iSOI) can induce bound states of two electrons in a one-dimensional quantum wire, with binding energies tunable by gate potential.

Contribution

It reveals that iSOI creates attractive interactions leading to two types of electron pairs, a novel mechanism for electron pairing in quantum wires.

Findings

Two-electron bound states can form due to iSOI overcoming Coulomb repulsion.

Binding energies are in the meV range and tunable by gate potential.

Two distinct types of bound states depend on the motion involved in iSOI.

Abstract

We solve a two-body problem for electrons in a one-dimensional system to show that two-electron bound states can arise as a result of the image-potential-induced spin-orbit interaction (iSOI). The iSOI contributes an attractive component to the electron-electron interaction Hamiltonian that competes with the Coulomb repulsion and overcomes it under certain conditions. We find that there exist two distinct types of two-electron bound states, depending on the type of the motion that forms the iSOI: the relative motion or the motion of the electron pair as a whole. The binding energy lies in the meV range for realistic material parameters and is tunable by the gate potential.