(BEDT-TTF)2Cu2(CN)3 Spin Liquid: Beyond the Average Structure

Pascale Foury-Leylekian (1) , Vita Ilakovac-Casses (2, 3) , Victor Balédent (1) , Pierre Fertey (4) , Alla Arakcheeva (5) , Ognjen Milat (6) , Denis Petermann (1) , Gilles Guillier (1) , Kazuya Miyagawa (7) , Kazushi Kanoda (7) , Pere Alemany (8) , Enric Canadell (9) , Silvia Tomic (6) , Jean-Paul Pouget (1)

1 LPS - Laboratoire de Physique des Solides
2 LCPMR - Laboratoire de Chimie Physique - Matière et Rayonnement
3 UCP - Université de Cergy Pontoise
4 SSOLEIL - Synchrotron SOLEIL
5 EPFL - Ecole Polytechnique Fédérale de Lausanne
6 Institute of Physics, Bijenicka cesta
7 UTokyo - The University of Tokyo
8 IQTCUB - Departament de Quimica Fisica and Institut de Quimica Teorica i Computacional
9 ICMAB - Institut de Ciència de Materials de Barcelona

We present here the first accurate determination of the exact structure of κ-(BEDT-TTF) 2 Cu 2 (CN) 3. Not only did we show that the room temperature structure used over the last twenty years was incorrect, but we were also able to correctly and precisely determine it. The results of our work provide evidence that the structure presents a triclinic symmetry with two non-equivalent dimers in the unit cell, which implies a charge disproportionation between the dimers. However, structural refinement shows that the charge disproportionation is quite weak at room temperature.

Keywords: mott transition; molecular spin liquids; geometrical frustration; X-ray diffraction; mott transition

Domains: Cristallography

Pascale Foury-Leylekian, Vita Ilakovac-Casses, Victor Balédent, Pierre Fertey, Alla Arakcheeva, et al.. (BEDT-TTF)2Cu2(CN)3 Spin Liquid: Beyond the Average Structure. Crystals, 2018, 8 (4), pp.158. ⟨10.3390/cryst8040158⟩. ⟨hal-01830162⟩