Entanglement and magnetism in high-spin graphene nanodisks

TL;DR

This paper studies the magnetic and entanglement properties of high-spin graphene nanodisks using advanced many-body techniques, revealing edge entanglement and tunable magnetism relevant for spintronics.

Contribution

It applies the density-matrix renormalization group to accurately analyze magnetism and entanglement in graphene nanodisks, surpassing mean-field limitations.

Findings

Edges are strongly entangled with each other.

Magnetic properties can be controlled by electric field.

Doping influences the magnetic behavior.

Abstract

We investigate the ground-state properties of triangular graphene nanoflakes with zigzag edge configurations. The description of zero-dimensional nanostructures requires accurate many-body techniques since the widely used density-functional theory with local density approximation or Hartree-Fock methods cannot handle the strong quantum fluctuations. Applying the unbiased density-matrix renormalization group algorithm we calculate the magnetization and entanglement patterns with high accuracy for different interaction strengths and compare them to the mean-field results. With the help of quantum information analysis and subsystem density matrices we reveal that the edges are strongly entangled with each other. We also address the effect of electron and hole doping and demonstrate that the magnetic properties of triangular nanoflakes can be controlled by electric field, which reveals features of flat-band ferromagnetism. This may open up new avenues in graphene based spintronics.