Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 72: Poster Session: Correlated Electrons
TT 72.37: Poster
Wednesday, March 14, 2018, 15:00–19:00, Poster B
Magnetism of the effective spin-1/2 chain compound Cs2CoCl4−xBrx — •Severin Kopatz1, Oliver Breunig1, Daniel Brüning1, Ladislav Bohatý2, Petra Becker2, and Thomas Lorenz1 — 1II. Physikalisches Institut, Universität zu Köln, Germany — 2Institut für Kristallographie, Universität zu Köln, Germany
Cs2CoCl4 contains CoCl4 tetrahedra, which form one-dimensional chains along the crystallographic b axis. The orbital groundstate of Co2+ (3d7, S=3/2) is split by a crystal field anisotropy D into two doublets and an easy-plane anisotropy of the magnetization is established and a description as an effective spin-1/2 XXZ chain arises. By considering thermal as well as virtual excitations of higher crystal field states, we find that the spin chain is in the XY-limit with an anisotropy Jz/J⊥≈ 0.12 substantially smaller than previously believed [1]. Below 300 mK antiferromagnetic order evolves and several new phases are induced in magnetic fields [2]. Cs2CoCl4 is isostructual to Cs2CuCl4−xBrx where site-selective doping was used to characterize quasi 2D quantum antiferromagnets with different degrees of magnetic frustration [3]. Here, we present specific-heat studies on bromine doped Cs2CoCl4−xBrx for different x. Funded by the DFG via CRC 1238 Projects A02 and B01.
[1] O. Breunig et al., Phys. Rev. Lett. 111, 187202 (2013)
[2] O. Breunig et al., Phys. Rev. B 91, 024423 (2015)
[3] P. T. Cong et al., Phys. Rev. B 83, 064425(2011)