Paired states of interacting electrons in a two dimensional lattice

TL;DR

This paper demonstrates that two repelling electrons in a 2D lattice can form bound pairs with unique energy and dynamic properties, potentially leading to a bosonic fluid that affects electrical resistance.

Contribution

It introduces the concept of bound electron pairs in a 2D lattice due to repulsion, revealing their energy scaling and dynamic behavior under electric fields.

Findings

Bound pairs form a band with energy proportional to interaction strength.

Paired states behave as composite particles with charge 2e.

Coexistence of single and paired states could enable bosonic fluid formation.

Abstract

We show that two tight binding electrons that repel may form a bounded pair in two dimensions. The paired states form a band with energies that scale like the strength of the interaction potential. By applying an electric field we show that the dynamics of such states is that of a composite particle of charge 2e. The system still sustains Bloch-like states, so that if the two bands overlap single and paired states might coexist allowing for a bosonic fluid component that, if condensed, would decrease the resistance at low temperatures. The presence of two bands allows for new oscillations whose experimental detection would permit a direct measurement of the interaction potential strength.