SKM 2023 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 43: Poster: Correlated Electrons II
TT 43.14: Poster
Wednesday, March 29, 2023, 15:00–18:00, P2/OG3
Order from disorder phenomena in BaCoS2 — •Benjamin Lenz1, Michele Fabrizio2, and Michele Casula1 — 1IMPMC, Sorbonne Université, CNRS, MNHN, 4 Place Jussieu, 75005 Paris, France — 2International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
We investigate different nematic and orbital ordered instabilities in the antiferromagnetic insulating phase of BaCoS2, which shows a Néel transition at a surprisingly high temperature of TN∼300 K. Based on ab initio simulations, we discuss several competing orders in terms of magnetic order, orbital composition and structural distortions to identify a set of nematic and orbital ordered states as possible candidates for the ground state. From these considerations we derive an effective spin model of J1−J2−J3 type and discuss the consequences of the most probable, orbital ordered ground state for its parametrization. We finally identify a driving mechanism which allows to explain the high Néel temperature by C4-symmetry breaking through orbital order and draw parallels to other quasi-2D materials such as pnictides.