Quantum frustration in organic Mott insulators: from spin liquids to unconventional superconductors

Understand

We review the interplay of frustration and strong electronic correlations in quasi-two-dimensional organic charge transfer salts, such as k-(BEDT-TTF)_2X and Et_nMe_{4-n}Pn[Pd(dmit)2]2.

• These two forces drive a range of exotic phases including spin liquids, valence bond crystals, pseudogapped metals, and unconventional superconductivity.
• Of particular interest is that in several materials there is a direct transition as a function of pressure from a spin liquid Mott insulating state to a superconducting state.
• Experiments on these materials raise a number of profound questions about the quantum behaviour of frustrated systems, particularly the intimate connection between spin liquids and superconductivity.