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TT: Fachverband Tiefe Temperaturen

TT 79: Correlated Electrons - Poster Session

TT 79.52: Poster

Wednesday, April 2, 2014, 15:00–19:00, P2

Specific heat studies of the Cs₂CuCl_4−xBr_x-system — •Markus Kuhnt, Natalija van Well, Franz Ritter, Pham Thanh Cong, Bernd Wolf, Michael Lang, Cornelius Krellner, and Wolf Assmus — Institute of Physics, Goethe-University Frankfurt, Max-von-Laue-Straße 1, D-60438 Frankfurt (M), Germany

In this contribution, we report on a systematic study of the magnetic properties on single crystals of the Cs₂CuCl_4−xBr_x-system (0≤ x≤ 4), which include the well studied end components Cs₂CuCl₄ and Cs₂CuBr₄. Both are S=1/2 quasi-two-dimensional-quantum antiferromagnets, but whereas Cs₂CuCl₄ exhibits field-induced Bose-Einstein-condensation, in Cs₂CuBr₄ triplet crystallization is found. In 2011 Cong et al. studied the magnetic susceptibility of the Cs₂CuCl_4−xBr_x-system (0≤ x≤ 4) above 2 K and found that the transition from Cs₂CuCl₄ to Cs₂CuBr₄ evolves discontinuously[1].

This discontinuous evolution motivates to study the magnetic properties of this system more thoroughly. Thus, we measured the specific heat at various x in the temperature range 1.8≤ T ≤ 20 K. We will discuss the magnetic part of the specific heat as well as the ratio between the maximum temperatures of magnetic specific heat and magnetic susceptibility as a function of x. These data will also be compared to theoretical calculations for Heisenberg antiferromagnetic chains and 2D Heisenberg triangular antiferromagnets.

[1] P.T. Cong et al., Phys. Rev. B 83, 064425