Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 10: Electron Theory of Magnetism and Correlations/Other Theory
MA 10.1: Vortrag
Montag, 18. März 2024, 15:00–15:15, EB 107
Broken-symmetry magnetic phases in two-dimensional triangulene crystals — João C. G. Henriques1,2, Gonçalo Catarina3, David Jacob4, Alejandro Molina-Sánchez5, •António T. Costa1, and Joaquín Fernández-Rossier1 — 1International Iberian Nanotechnology Laboratory, Braga, Portugal — 2Universidade de Santiago de Compostela, Santiago de Compostela, Spain — 3Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland — 4Universidad del País Vasco, San Sebastián, Spain — 5University of Valencia, Valencia, Spain
We provide a theory of magnetic phases in 2D triangulene crystals, using both Hubbard model and density functional theory (DFT) calculations. We consider centrosymmetric, non-centrosymmetric and nitrogen-doped triangulene crystals. In the undoped cases, DFT and mean-field Hubbard model predict the emergence of broken-symmetry antiferromagnetic and ferrimagnetic phases. We also compute the spin wave spectrum of these crystals.The results are in excellent agreement with the predictions of a Heisenberg spin model derived from multi-configuration calculations for the unit cell.
For the N-doped case we show that the low energy excitations include strongly coupled spin and orbital degrees of freedom. The key ingredient is the existence of orbital degeneracy, which forces us to leave the benzenoid/half-filling scenario. We find a rich interplay between orbital and spin degrees of freedom that confirm the need to go beyond the spin-only paradigm.
Keywords: carbon magnetism; magnons; 2D magnetic crystals; orbital degeneracy