Anions effects on the electronic structure and electrodynamic properties   of the Mott insulator $\kappa$-(BEDT-TTF)$_2$Ag$_2$(CN)$_{3}$
  The Mott insulator $\kappa$-(BEDT-TTF)$_2$Ag$_2$(CN)$_3$ forms a highly-frustrated triangular lattice of $S=1/2$ dimers with a possible quantum-spin-liquid state. Our experimental and numerical studies reveal the emergence of a slight charge imbalance between crystallographically inequivalent sites, relaxor dielectric response and hopping dc transport. In a broader perspective we conclude that the universal properties of strongly-correlated charge-transfer salts with spin liquid state are an anion-supported valence band and cyanide-induced quasi-degenerate electronic configurations in the relaxed state. The generic low-energy excitations are caused by charged domain walls rather than by fluctuating electric dipoles. They give rise to glassy dynamics characteristic of dimerized Mott insulators, including the sibling compound $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$. 
M. Pinteri\'c, P. Lazi\'c, A. Pustogow, T. Ivek, M. Kuve\v{z}di\'c, O.   Milat, B. Gumhalter, M. Basleti\'c, M. \v{C}ulo, B....
cond-mat.str-el