Triangular-Lattice Organic Mott Insulator with a Disorder-Free Polyanion

Abstract

We report the synthesis, crystal and band structures, and transport properties of organic conductor κ-(ET) 2 Cu[Au(CN) 2 ]Cl [ET = bis(ethylenedithio)tetrathiafulvalene], which has a triangular spin−lattice (S = 1 / 2 ) composed of (ET) 2•+ dimers and polyanions with no disorder. The anisotropy of triangular lattice t′/t = 1.19 and physical properties indicate that this material is the first ET-based quantum-spin-liquid candidate having a nearly regular triangular lattice with a disorder-free anion.

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

“…The triangular coordination of Cu and Ag implies frustration since each Cu/Ag atom can be linked either to two N and one C atom, or to one N atom and two C atoms introducing intrinsic disorder. This ambiguity was eliminated in the recently synthesized salt κ-(BEDT-TTF) 2 Cu[Au(CN) 2 ]Cl that is highly frustrated t /t = 1.19 but possesses no disorder in the polymeric anions [74]. It is worth to note that in contrast to many other BEDT-TTF salts, in the present family, i.e.…”

“…However, the formation of a disordered valence-bond solid implying the opening of a spin gap could be a general scenario [190,503,585,586]. In this regard, the recently synthesized compound κ-(BEDT-TTF) 2 Cu[Au(CN) 2 ]Cl is of interest as it possesses no disorder in the anions [74].…”

Organic quantum materials: A review

“…To avoid structural disorder, Tomeno et al 215 prepared the first disorder‐free QSL candidate κ‐(ET) 2 CuAuCN 2 Cl, where an isotropic triangular spin‐lattice system was formed. Positive pressure dependence of Mott transition temperature strongly confirmed its QSL state.…”