Mesoscopic frustrated phase separation in electronic systems

PACS. 64.75.+g – Solubility, segregation, and mixing; phase separation. PACS. 71.10.Hf – Non-Fermi-liquid ground states, electron phase diagrams and phase transi-tions in model systems. PACS. 71.10.Ca – Electron gas, Fermi gas. Abstract. – We analyze phase separation (PS) among two electronic phases, frustrated by the long-range Coulomb interaction. We define a dimensionless parameter λ which characterizes the degree of frustration. Frustrated PS appears abruptly as a function of the global electronic density and exhibits strong nonlinearities as compared with ordinary PS. Inhomogeneities of one phase, hosted by the other phase, result on a scale of the order of or smaller than the electric-field screening length. In general above a critical λ the system remains in a single phase except close to a critical electronic density where PS among neutral phases is accompanied by a lattice instability. Ordinary phase separation (PS) is a generic phenomenon in density-driven first-order phase transitions. If the global density n is constrained in the “miscibility gap ” (n0A < n < n