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The promotion of collinear classical spin configurations as well as the enhanced tendency towards nearest-neighbor clustering of the quantum spins are typical features of the frustrating isotropic three-body exchange interactions in…

Strongly Correlated Electrons · Physics 2016-05-16 N. B. Ivanov , S. I. Petrova , J. Schnack

Tailor-made graphene nanostructures can exhibit symmetry-protected topological boundary states that host localized spin-$1/2$ moments. However, one frequently observes charge transfer on coinage metal substrates, which results in spinless…

Open-shell nanographenes offer a controlled setting to study correlated magnetism emerging from $\pi$-electron systems. We analyze oligo(indenoindene) molecules, non-bipartite carbon ladders whose tight-binding spectra feature a gapped,…

Mesoscale and Nanoscale Physics · Physics 2025-12-23 Andoni Agirre , Thomas Frederiksen , Geza Giedke , Tobias Grass

Motivated by recent experimental data (Sepioni, M. et al. Phys. Rev. Lett. 2010, 105, 207205), we have studied the possibility of forming magnetic clusters with spin S> 1/2 on graphene by adsorption of hydrogen atoms or hydroxyl groups.…

Mesoscale and Nanoscale Physics · Physics 2011-11-08 D. W. Boukhvalov , M. I. Katsnelson

Hydrogenated graphene, graphane, is studied on oxygen-terminated silicon dioxide substrate using ab initio calculations. A structure with hydrogenation only on one side of the graphene layer is found stable and its hydrogen configurations…

Mesoscale and Nanoscale Physics · Physics 2011-07-13 M. Ijäs , P. Havu , A. Harju , P. Pasanen

Magnetic interactions between localized spins-1/2 play a central role in quantum magnetism, spin-based quantum computing, and quantum simulation. The range and strength of these interactions are key figures of merit. Here, we probe exchange…

The simple Hubbard Hamiltonian with the mean field approximation is used to know about the energy bands and spin susceptibilities of zigzag graphene nanoribbons. Depending on the electron doping, antiferromagnetic or ferromagnetic…

Mesoscale and Nanoscale Physics · Physics 2015-06-03 Juan-Antonio Casao-Perez

The study of open-shell nanographenes has relied on a paradigm where spins are the only low-energy degrees of freedom. Here we show that some nanographenes can host low-energy excitations that include strongly coupled spin and orbital…

Mesoscale and Nanoscale Physics · Physics 2023-12-11 J. C. G. Henriques , D. Jacob , A. Molina-Sánchez , G. Catarina , A. T. Costa , J. Fernández-Rossier

Understanding and engineering the coupling of spins in nanomaterials is of central importance for designing novel devices. Graphene nanostructures with {\pi}-magnetism offer a chemically tunable platform to explore quantum magnetic…

We consider the one dimensional, periodic spin chain with $N$ sites, similar to the one studied by Haldane \cite{hal}, however in the opposite limit of very large anisotropy and small nearest neighbour, anti-ferromagnetic exchange coupling…

Strongly Correlated Electrons · Physics 2015-06-19 S. A. Owerre , M. B. Paranjape

We study the ground state properties of an ABA-stacked trilayer graphene. The low energy band structure can be described by a combination of both a linear and a quadratic particle-hole symmetric dispersions, reminiscent of monolayer- and…

Mesoscale and Nanoscale Physics · Physics 2012-03-08 Ralph van Gelderen , Lih-King Lim , C. Morais Smith

We propose a mechanism to drive singlet-triplet spin transitions electrically, in a wide class of graphene nanostructures that present pairs of in-gap zero modes, localized at opposite sublattices. Examples are rectangular nanographenes…

Mesoscale and Nanoscale Physics · Physics 2018-05-23 R. Ortiz , N. A. García-Martínez , J. L. Lado , J. Fernández-Rossier

Unlocking the potential of topological order within many-body spin systems has long been a central pursuit in the realm of quantum materials. Despite extensive efforts, the quest for a versatile platform enabling site-selective spin…

Spin-hosting graphene nanostructures are promising metal-free systems for elementary quantum spintronic devices. Conventionally, spins are protected from quenching by electronic bandgaps, which also hinder electronic access to their quantum…

The antiferromagnetic Heisenberg spin chain with integer spin has short-range magnetic order and an excitation energy gap above the ground state. This so-called Haldane gap is proportional to the exchange coupling $J$ of the Heisenberg…

Strongly Correlated Electrons · Physics 2019-07-19 Thierry Jolicoeur , Olivier Golinelli

We propose how to form spin qubits in graphene. A crucial requirement to achieve this goal is to find quantum dot states where the usual valley degeneracy in bulk graphene is lifted. We show that this problem can be avoided in quantum dots…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 B. Trauzettel , Denis V. Bulaev , Daniel Loss , Guido Burkard

First-principles calculations of the spin-orbit coupling in graphene with hydrogen adatoms in dense and dilute limits are presented. The chemisorbed hydrogen induces a giant local enhancement of spin-orbit coupling due to $sp^3$…

Mesoscale and Nanoscale Physics · Physics 2013-06-18 Martin Gmitra , Denis Kochan , Jaroslav Fabian

Graphene has emerged as the foremost material for future two-dimensional spintronics due to its tuneable electronic properties. In graphene, spin information can be transported over long distances and, in principle, be manipulated by using…

Spin excitation in a nano-graphite ribbon with zigzag edges is investigated theoretically. Due to the strongly localized nature of the states near Fermi energy, the effective Hamiltonian for the low energy physics is given by Heisenberg…

Strongly Correlated Electrons · Physics 2009-11-10 H. Yoshioka

Proximity-induced spin-orbit coupling in graphene has led to the observation of intriguing phenomena like time-reversal invariant $\mathbb{Z}_2$ topological phase and spin-orbital filtering effects. An understanding of the effect of…

Mesoscale and Nanoscale Physics · Physics 2022-10-18 Priya Tiwari , Mohit Kumar Jat , Adithi Udupa , Deepa S. Narang , Kenji Watanabe , Takashi Taniguchi , Diptiman Sen , Aveek Bid