Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Correlated Magnetism – Low-Dimensional Systems

TT 9.8: Talk

Monday, March 17, 2025, 17:00–17:15, H33

First-principles phonon study of AgCrS₂, AgCrSe₂, and AgCrTe₂ — •Seo-Jin Kim, Jörg Sichelschmidt, Michael Baenitz, Yurii Prots, Markus Schmidt, and Helge Rosner — Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

We study the elastic and dynamic stability of layered triangular lattice systems AgCrS₂, AgCrSe₂, and AgCrTe₂ using density functional theory (DFT). These systems share the same structure but exhibit different properties. Multiferroic AgCrS₂ undergoes an additional structural transition to a monoclinic phase and exhibits a collinear double-stripe antiferromagnetic ground state below T_N = 42 K. AgCrSe₂ shows noncollinear cycloidal magnetic ordering below T_N = 32 K. To investigate the interplay between magnetism and structure, we analyze the elastic constants and phonon dispersions of these compounds. Our findings reveal that the on-site Coulomb repulsion and additional symmetry alterations in the Cr layer are crucial for achieving dynamical stability in AgCrS₂. Furthermore, we analyze AgCrSe₂ and AgCrTe₂ to understand the general trends in elastic and dynamic properties with chalcogen variation.

Keywords: DFT; phonon; triangular lattice