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TT: Fachverband Tiefe Temperaturen
TT 65: Poster Session Topological Topics
TT 65.30: Poster
Donnerstag, 19. März 2020, 15:00–19:00, P2/EG
Magnetic properties of spin chain materials Cs2Co(Cl/Br)4 — •Thomas Leich1, Daniel Brüning1, Ladislav Bohatý2, Petra Bohatý2, Oliver Breunig1, and Thomas Lorenz1 — 1II. Physikalisches Institut, Universitat zu Köln — 2Institut für Kristallographie, Universität zu Köln
Cs2CoCl4 has been identified as an effective spin-1/2 chain material with strong XY anisotropy [1]. Due to inter-chain coupling it shows long-range magnetic order below 0.23 K with complex phase diagrams up to magnetic fields of 2.5 T [2]. Here we present a study of the isostructural substitution series Cs2CoCl4−xBrx. Cs2CoBr4 shows some similar phases, but they are more stable and extend to tempeatures up to 1.35 K and magnetic fields up to 4 T. Measuring specific heat, magnetocaloric effect, thermal expansion and magnetization at temperatures down to 250 mK, the magnetic order of the different phases is characterized, as the material shows strong magnetic field dependence of magnetization, entropy and magnetostriction coefficient. We present phase diagrams for different field directions and discuss the origin of the phases. The 1D spin-chain physics is partly covered by the 3D magnetic order, and an increased single-ion anisotropy of about 20 K is determined, compared to 13.9 K in Cs2CoCl4.
Funded by DFG via Project No. 277146847 - CRC 1238
[1] O. Breunig et al., PRL 111, 187202 (2013)
[2] O. Breunig et al., PRB 91, 024423 (2015)