Coulomb pairing of electrons in thin films with strong spin-orbit interaction

TL;DR

This paper investigates how strong Rashba spin-orbit interaction in thin films can lead to attractive electron-electron interactions and bound states, with dielectric screening enhancing the binding energy compared to bulk materials.

Contribution

It demonstrates that in thin films with high Rashba SOI, Coulomb pairing can occur, revealing a new mechanism for electron pairing influenced by spin-orbit effects.

Findings

Strong Rashba SOI can induce attractive electron interactions.

Dielectric screening in thin films increases binding energy.

Formation of two-electron bound states due to Coulomb pairing.

Abstract

In low-dimensional structures with strong Rashba spin-orbit interaction (SOI), the Coulomb fields between moving electrons produce a SOI component of the pair interaction that competes with the potential Coulomb repulsion. If the Rashba SOI constant of the material is sufficiently high, the total electron-electron interaction becomes attractive, which leads to the formation of the two-electron bound states. We show that because of the dielectric screening in a thin film the binding energy is significantly higher as compared to the case of the bulk screening.