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TT: Fachverband Tiefe Temperaturen

TT 17: Poster Session: Correlated Electrons 1

TT 17.35: Poster

Montag, 1. April 2019, 15:00–18:30, Poster D

Single-crystal growth and magnetic phase diagram of Li₂FeSiO₄ — •Waldemar Hergett¹, Christoph Neef¹, Sven Sauerland¹, Martin Jonak¹, Mahmoud Abdel-Hafiez¹, Hubert Wadepohl², Clemens Ritter³, and Rüdiger Klingeler¹ — ¹Kirchhoff Institute of Physics, Heidelberg University — ²Institute of Inorganic Chemistry, Heidelberg University — ³Institut Laue-Langevin, Grenoble

By using the high-pressure optical floating-zone technique (FZ), mm-sized single crystals of γ_II-Li₂FeSiO₄ (space group Pmnb) were grown and characterized for the first time. Oriented cuboids were used for thermal expansion, specific heat, and magnetisation studies. High-resolution neutron powder diffraction experiments were performed to resolve the magnetic ground state and analyse the Li-Fe antisite disorder. The impact of different synthesis routes of the starting materials and of FZ growth parameters on the crystal quality was investigated. The single crystal structure of the Pmnb-polymorph was solved for the first time. Thermal expansion, magnetisation and specific heat data show a sharp λ-like anomaly associated with the onset of long-range antiferromagnetic order at T_N=17.0(5) K. Pulsed-field magnetisation studies up to 60 T enable constructing the magnetic phase diagram.