Double single-channel Kondo coupling in graphene with Fe molecules

TL;DR

This paper investigates the Kondo effect in graphene coupled with Fe molecules, revealing a channel decoupling phenomenon that leads to two nearly independent Kondo systems influenced by graphene's charge state.

Contribution

It introduces a channel selective tunneling Hamiltonian for Fe molecules on graphene, showing how spin interactions lead to decoupled Kondo channels near the Dirac point.

Findings

Channel selectivity causes decoupling of Kondo interactions.

Magnetic moments and Kondo effect depend on graphene's charge state.

Two nearly independent Kondo systems are identified.

Abstract

We study the interaction between graphene and a single-molecule-magnet, [Fe4(L)2(dpm)6]. Focusing on the closest Iron ion in a hollow position with respect to the graphene sheet, we derive a channel selective tunneling Hamiltonian, that couples different d orbitals of the Iron atom to precise independent combinations of sublattice and valley degrees of freedom of the electrons in graphene. When looking at the spin-spin interaction between the molecule and the graphene electrons, close to the Dirac point the channel selectivity results in a channel decoupling of the Kondo interaction, with two almost independent Kondo systems weakly interacting among themselves. The formation of magnetic moments and the development of a full Kondo effect depends on the charge state of the graphene layer.