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MA: Fachverband Magnetismus

MA 19: POSTER Ia

MA 19.3: Poster

Dienstag, 17. März 2015, 09:30–13:00, Poster A

Magnetic properties of the covalent chain antiferromagnets RbFeSe₂ and TlFeX₂ (X=S, Se) — •Zakir Seidov^1,2, Vladimir Tsurkan^2,3, Hans-Albrecht Krug von Nidda², Axel Günther², Irina Filipova³, and Alois Loidl² — ¹Institute of Physics, Azerbaijan National Academy of Sciences, H.Cavid ave.131, AZ-1143 Baku, Azerebaijan — ²EP V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86159 Augsburg, Germany — ³Institute of Applied Physics, Academy of Sciences of Moldova, MD-202208 Chisinau, Moldova

Single crystals of the ternary iron chalcogenides RbFeSe₂, TlFeS₂, and TlFeSe₂ (with linear chains consisting of FeX₄ tetrahedra, X=S, Se) have been investigated by means of magnetic susceptibility, magnetization, specific heat and ESR measurements. All three compounds exhibit three-dimensional collinear antiferromagnetic order with strongly reduced moments below T_N=248K, 196K, and 290K, respectively. The magnetic moments are oriented perpendicular to the chain direction. The specific heat measurements of TlFeX₂ (X=S, Se) do not show any anomaly at T_N[1], while there is a λ anomaly in RbFeSe₂. However, the calculated entropy value for RbFeSe₂ is much smaller than expected for a low-spin S=1/2 Fe³⁺ spin system. The linear increase of the paramagnetic susceptibility and ESR intensity of RbFeSe₂ and TlFeX₂ (X=S, Se) strongly suggests a one-dimensional metallic character.
[1] M.Aldzhanov et al., phys. stat. sol. (b) 159, 1990, K107.