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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.77: Poster

Mittwoch, 24. März 2010, 14:00–18:00, Poster D1

Derivation of the effective microscopic models for the frustrated antiferromagnets Cs₂CuCl₄ and Cs₂CuBr₄ from first principles — •Kateryna Foyevtsova, Ingo Opahle, Harald Jeschke, and Roser Valenti — Institut für Theoretische Physik, Goethe-Universität Frankfurt, 60438 Frankfurt am Main, Germany

The frustrated antiferromagnets Cs₂CuCl₄ and Cs₂CuBr₄ have been attracting a lot of attention as low-dimensional quantum systems with a variety of unconventional properties, such as, for instance, the spin-liquid state in Cs₂CuCl₄ or magnetization plateaux in Cs₂CuBr₄.

In order to provide a theoretical insight to the on-going discussion of the Cs₂CuCl₄ and Cs₂CuBr₄ effective models, we perform a comprehensive Density Functional Theory (DFT) study of the electronic properties of Cs₂CuCl₄ and Cs₂CuBr₄ and derive the tight-binding (TB) and Heisenberg models’ parameters for the two compounds. We find that in Cs₂CuCl₄ electronic correlations play an important role for the correct description of the crystal structure and discuss the implications of such results for DFT calculations with commonly-used approximations for the exchange-correlation functional.