Superexchange Mechanism in Coupled Triangulenes Forming Spin-1 Chains

Abstract

We show that the origin of the antiferromagnetic coupling in spin-1 triangulene chains, which were recently synthesized and measured by Mishra et al. Nature 598, 287-292 (2021) originates from a superexchange mechanism. This process, mediated by inter-triangulene states, opens the possibility to control parameters in the effective bilinear-biquadratic spin model. We start from the derivation of an effective tight-binding model for triangulene chains using a combination of tight-binding and Hartree-Fock methods fitted to hybrid density functional theory results. Next, correlation effects are investigated within the configuration interaction method. Our low-energy many-body spectrum for $N_{\mathrm{Tr}}=2$ and $N_{\mathrm{Tr}}=4$ triangulene chains agree well with the bilinear-biquadratic spin-1 chain antiferromagnetic model when indirect coupling processes, and superexchange coupling between triangulene spins are taken into account.

References in corpus (12)

• The electronic properties of graphene
• Magnetism in graphene nano-islands
• Metallic Graphene Nanodisks
• Implementation of Spin Hamiltonians in Optical Lattices
• Spin nematic correlations in bilinear-biquadratic S=1 spin chains
• Coulomb Blockade in Graphene Nanodisks
• Theory of intermolecular exchange in coupled spin-1/2 nanographenes
• Theory of triangulene two-dimensional crystals
• Hubbard model for spin-1 Haldane chains
• Broken-symmetry magnetic phases in two-dimensional triangulene crystals
• Electrically driven singlet-triplet transition in triangulene spin-1 chains
• Quantum Monte Carlo Study of Semiconductor Artificial Graphene Nanostructures

Cited by in corpus (3)

• Conformational tuning of magnetic interactions in coupled nanographenes
• Quantum Monte Carlo study of artificial triangular graphene quantum dots
• Graphene-based quantum heterospin graphs