Regensburg 2019 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 6: Frustrated Magnets - Spin Liquids (joint session TT/MA)
MA 6.13: Vortrag
Montag, 1. April 2019, 18:15–18:30, Theater
Randomness in the quantum spin liquid candidate κ-(BEDT-TTF)2Cu2(CN)3 investigated by artificial distortion of the triangular lattice — •Yohei Saito1, Andrej Pustogow1, Roland Rösslhuber1, Miriam Alonso1, Maxim Wenzel1, Anja Löhle1, Martin Dressel1, Takaaki Minamidate2, Noriaki Matsunaga2, Kazushige Nomura2, and Atsushi Kawamoto2 — 11. Physikalisches Inst., Universität Stuttgart, Germany — 2Department of Physics, Hokkaido University, Sappro, Japan
The organic-molecular solid κ-(BEDT-TTF)2Cu2(CN)3 is recognized as a quantum spin liquid candidate as it does not show magnetic ordering regardless of the large magnetic interactions. There is a debate about the importance of spin frustration on the triangular lattice and inherent randomness in the crystals. Does a suppression of geometrical frustration change the magnetic properties? To clarify that, we artificially distorted triangular lattices of κ-(BEDT-TTF)2Cu2(CN)3 by donor molecular substitution that modifies exchange interactions. As a result, geometrical frustration is suppressed locally. We performed electric conductivity, dielectric spectroscopy, infrared spectroscopy, and 13C NMR measurements. Comparing results of non-substituted and substituted samples, we found that their magnetic fluctuation was the same as opposed to the remarkable impurity substitution effect of the conductivity. Thus, the electronic state of the (CN)3 salt is already disordered even in the non-substituted sample, and that not only the ideal geometrical frustration but also the disorder effect should be considered.