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arXiv · 2605.24078

Controlling spin-$\frac 12$ antiferromagnetic interaction strength in nanographene dimers

Robiatul Adawia·Pawel Tecmer·Pawel Potasz
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Abstract

We demonstrate that the effective spin-exchange coupling $J$ in open-shell nanographene dimers can be precisely tuned via tip-induced dehydrogenation of selected carbon atoms. Using the double ionization potential equation-of-motion coupled-cluster singles and doubles (DIP-EOM-CCSD) method, we accurately compute the singlet-triplet gaps, which correspond directly to the exchange coupling $J$. We show that the position of the dehydrogenated (or hydrogen-passivated) site in triangulene dimers strongly modulates the singlet-triplet splitting, allowing $J$ to be tuned over a wide range - from a few meV to several tens of meV. This strategy provides a simple yet powerful route for designing tailored spin models with alternating or spatially patterned spin-exchange couplings.

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Robiatul Adawia, Pawel Tecmer, Pawel Potasz. 2026-05-22. Controlling spin-$\frac 12$ antiferromagnetic interaction strength in nanographene dimers. https://arxiv.org/abs/2605.24078

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