Modelling spin qubits in carbon peapods

TL;DR

This study models electron spin interactions in chains of endohedral fullerenes within carbon nanotubes, revealing that spins mainly reside on the fullerenes and interact via an antiferromagnetic Heisenberg chain, unaffected by nanotube type.

Contribution

It provides a detailed computational analysis of spin interactions in fullerene-based chains inside nanotubes, introducing a simplified model that accurately predicts exchange interactions.

Findings

Spin mainly resides on fullerene cages.

Spin interactions decay exponentially with distance.

Nanotube type does not affect spin interactions.

Abstract

We have calculated electron spin interactions in chains of Sc@C82 endohedral fullerenes in isolation and inserted into a semiconducting or metallic single-walled carbon nanotube to form a peapod. Using hybrid density functional theory (DFT), we find that the spin resides mainly on the fullerene cage, whether or not the fullerenes are in a nanotube. The spin interactions decay exponentially with fullerene separation, and the system can be described by a simple antiferromagnetic Heisenberg spin chain. A generalised Hubbard-Anderson model gives an exchange parameter J and a Coulomb parameter U in good agreement with the DFT values. Within the accuracy of the calculations, neither semiconducting nor metallic nanotubes affect the interactions between the fullerene electron spins.