Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 15: Poster I

MA 15.31: Poster

Tuesday, March 18, 2025, 10:00–12:30, P1

Frustrated magnetism in hydrogenated hexagonal Boron Nitride — •Maksim Ulybyshev, Manish Verma, and Giorgio Sangiovanni — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany

We study monolayer hexagonal boron nitride (h-BN) with hydrogen adatoms arranged in a regular triangular lattice. Extensive density functional theory (DFT) calculations reveal a flat band formed by electronic states localized near the adatoms, situated within the band gap of h-BN. Based on these results, we construct a tight-binding model that captures the essential features of this band structure and derive an effective Hamiltonian for electrons in the flat band. This effective Hamiltonian incorporates the effects of long-range Coulomb interactions projected onto the flat band using a technique previously validated by Quantum Monte Carlo simulations of similar systems. We demonstrate that the lack of particle-hole symmetry in this system causes the projected long-range Coulomb interactions to induce frustrated spin couplings between electrons localized near neighboring adatoms. Depending on the spatial configuration of the adatoms, this frustration can give rise to various nontrivial magnetic states.

Keywords: Hexagonal Boron Nitride; Spin Liquid; Coulomb interaction