SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Frustrated Magnets: General

TT 29.3: Vortrag

Mittwoch, 29. März 2023, 10:00–10:15, HSZ 201

Weakly coupled triangles forming a star lattice in an organic-inorganic copper sulfate — •Oleg Janson¹, Ulrich K. Rößler¹, and Hajime Ishikawa² — ¹Leibniz IFW Dresden, Germany — ²ISSP, University of Tokyo, Japan

The recently synthesized organic-inorganic copper sulfate [(CH₃)₂(NH₂)]₃[Cu₃(OH)(SO₄)₄]·0.24H₂O has been proposed as a material realization of the S=1/2 star lattice model [1]. We report high-field magnetization measured on powder samples showing a broad plateau at 1/3 of the saturation magnetization. Full saturation was reached at about 105 T in a destructive pulsed-field experiment. Low-field and low-temperature measurements on single crystals show no indications of magnetic ordering and reveal a sizable anisotropy of magnetization. Density-functional-theory (DFT) calculations indicate the relevance of two inequivalent exchanges J_T and J_D with J_T≫J_D, placing this material in the limit of weakly coupled triangles. Anisotropic components of J_T were estimated by noncollinear DFT+U calculations. We demonstrate that a simple model of isolated triangles accounts for the thermodynamic behavior of this compound.
[1] M. Sorolla et al., J. Am. Chem. Soc. 142, 5013 (2020)