Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 55: Correlated Electrons: Low-Dimensional Systems -Materials 2
TT 55.11: Vortrag
Donnerstag, 14. März 2013, 12:15–12:30, H21
Magnetic-ordering transitions of the effective XY-spin-1/2 compound Cs2CoCl4 — •Oliver Breunig1, Eran Sela2, Achim Rosch2, Benjamin Buldmann2, Petra Becker3, Ladislav Bohatý3, Sandra Niesen1, Ralf Müller1, and Thomas Lorenz1 — 1II. Physikalisches Institut, Universität zu Köln — 2Institut für Theoretische Physik, Universität zu Köln — 3Institut für Kristallographie, Universität zu Köln
Cs2CoCl4 is a model system for studying the magnetism of one-dimensional spin chains with an XY-like anisotropy. It contains CoCl4 tetrahedra which form chains along the crystallographic b axis. Due to a strong crystal field, an easy-plane anisotropy of magnetization is established. For symmetry reasons, easy planes in Cs2CoCl4 appear in two orientations. At temperatures between 0.3 and 4 K, the compound is well described by the one-dimensional XXZ model. At lower temperatures magnetic order arises due to finite inter-chain coupling. Our measurements of thermal expansion and specific heat down to 50 mK and in magnetic fields up to 3 T reveal a field-dependent ordering temperature TC(H). Depending on the orientation of the magnetic field with respect to the easy planes’ orientation various ordered phases arise. We present phase diagrams for different field directions and discuss possible ordering mechanisms.
This work was supported by the DFG through SFB 608.