Correlated electron states and transport in triangular arrays

We study correlated electron states in frustrated geometry of a triangular lattice. The interplay of long-range interactions and finite residual entropy of a classical system gives rise to unusual effects in equilibrium ordering as well as in transport. A correlated fluid phase is identified in a wide range of densities and temperatures above freezing into commensurate solid phases. The charge dynamics in the correlated phase is described in terms of a height field, its fluctuations, and topological defects. We demonstrate that the height field fluctuations give rise to a “free” charge flow and finite dc conductivity. We show that freezing into the solid phase, controlled by the long-range interactions, manifests itself in singularities of transport properties.