Superexchange Mechanism in Coupled Triangulenes Forming Spin-1 Chains
Yasser Saleem, Torben Steenbock, Emha Riyadhul Jinan Alhadi, Weronika Pasek, Gabriel Bester, Paweł Potasz
Abstract
High Resolution Image Download MS PowerPoint Slide 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 2021, 598, 287−292), originates from a superexchange mechanism. This process, mediated by intertriangulene 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 Tr = 2 and N 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.