Mesoscopic frustrated phase separation in electronic systems

We analyze phase separation (PS) among two electronic phases, frustrated by the long-range Coulomb interaction. We define a dimensionless parameter lambda 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 lambda 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.