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MA: Fachverband Magnetismus
MA 45: Computational Magnetism
MA 45.5: Vortrag
Freitag, 21. März 2025, 10:30–10:45, H18
Semiclassical approach to the exchange interactions and spin waves in double-layered antiferromagnets — Seo-Jin Kim1, Zdeněk Jirák2, Jiří Hejtmánek2, Karel Knížek2, Helge Rosner1, and •Kyo-Hoon Ahn2 — 1Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany — 2Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czechia
We investigate the stability and magnonic properties of double-layered antiferromagnets using two model systems—the linear chain (LC) and a more complex railroad trestle (RT) geometry—as well as the real solid antiferromagnetic (AFM) CrN in its rock-salt structure. In the LC model, the spin-paired order (⋯++−−⋯) requires alternating ferromagnetic (FM) and AFM interactions. In contrast, the RT geometry allows some frustration, and the spin-paired order can be stable even for all magnetic exchange interactions being AFM. In the hypothetical cubic phase of CrN, magnetic Cr ions form a face-centered cubic lattice with equivalent AFM links to twelve nearest neighbors. However, the magnetostructural transition to an orthorhombically distorted phase below the Néel temperature (TN = 287 K) diversifies the Cr-Cr nearest-neighbor distances, suppressing frustration. Using ab initio exchange parameters, we calculate the magnon dispersion relation and the temperature-dependent evolution of ordered magnetic moments. Our findings demonstrate that the stability of the double-layered AFM structure in CrN is attained, even when intra-sublattice interactions remain all AFM, consistent with the RT model.
Keywords: magnon; spin wave; double-layered antiferromagnet; ab initio calculation; CrN