Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 34: Computational Magnetism I
MA 34.2: Talk
Wednesday, March 11, 2026, 15:15–15:30, HSZ/0004
Spin waves in double-layered antiferromagnets: insights from chain models and application to CrN — 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
The stability and magnonic properties of double-layered antiferromagnets are examined using two model systems, the linear chain (LC) and the railroad trestle (RT) geometry, and compared with the behavior of the real solid CrN. In the LC, the spin-paired order (⋯++−−⋯) requires alternating ferromagnetic and antiferromagnetic (AFM) exchanges, whereas in the RT geometry an analogous order remains stable even with purely AFM interactions under specific analytical conditions. In CrN, the rock-salt structure causes strong magnetic frustration because each Cr atom has twelve symmetry-equivalent AFM nearest neighbors. Below TN=287 K, however, a magnetostructural transition to an orthorhombically distorted phase generates four distinct Cr-Cr distances and, consequently, a broad distribution of exchange strengths. This diversification suppresses frustration and stabilizes the double-layered AFM order. We trace this behavior to the competition between Cr–Cr direct exchange and 90∘ Cr–N–Cr superexchange, both exhibiting characteristic power-law dependencies on the interatomic distances. Finally, using ab initio exchange parameters, we derive the magnon spectrum and the temperature evolution of the ordered moments.
Keywords: magnon; spin wave; double-layered antiferromagnet; ab initio calculation; CrN